Refactor into monorepo

21 files changed, 3016 insertions, 0 deletions

diff --git a/pit/src/arena.c b/pit/src/arena.c
new file mode 100644
index 0000000..aedf0fb
--- /dev/null
+++ b/pit/src/arena.c
@@ -0,0 +1,60 @@
+#include <lcq/pit/arena.h>
+#include <lcq/pit/utils.h>
+
+pit_arena *pit_arena_new(u8 *buf, i64 buf_len, i64 elem_size) {
+    uintptr_t base = (uintptr_t) buf;
+    uintptr_t aligned = pit_align_up(base, sizeof(void *));
+    pit_arena *a = (pit_arena *) aligned;
+    uintptr_t data = aligned + sizeof(pit_arena);
+    i64 offset = (i64) data - (i64) base;
+    i64 remaining = (i64) pit_align_down((uintptr_t) (buf_len - offset), sizeof(void *));
+    if (!a || remaining <= 0) return NULL;
+    a->elem_size = elem_size;
+    a->capacity = remaining;
+    a->next = 0;
+    a->back = remaining;
+    return a;
+}
+void pit_arena_reset(pit_arena *a) {
+    a->next = 0;
+    a->back = a->capacity;
+}
+static i64 pit_arena_byte_idx(pit_arena *a, pit_arena_index idx) {
+    i64 byte_idx = 0; pit_mul(&byte_idx, a->elem_size, idx);
+    return byte_idx;
+}
+pit_arena_index pit_arena_alloc_index(pit_arena *a) {
+    i64 ret = a->next;
+    i64 byte_idx = pit_arena_byte_idx(a, ret);
+    if (byte_idx + a->elem_size >= a->back) { return -1; }
+    a->next += 1;
+    return ret;
+}
+pit_arena_index pit_arena_alloc_array_index(pit_arena *a, i64 num) {
+    i64 ret = a->next;
+    i64 byte_idx = pit_arena_byte_idx(a, ret);
+    i64 byte_len = 0; pit_mul(&byte_len, a->elem_size, num);
+    if (byte_idx + byte_len > a->back) { return -1; }
+    a->next += num;
+    return ret;
+}
+void *pit_arena_alloc(pit_arena *a) {
+    return pit_arena_get(a, pit_arena_alloc_index(a));
+}
+void *pit_arena_alloc_array(pit_arena *a, i64 num) {
+    return pit_arena_get(a, pit_arena_alloc_array_index(a, num));
+}
+
+void *pit_arena_get(pit_arena *a, pit_arena_index idx) {
+    i64 byte_idx = pit_arena_byte_idx(a, idx);
+    if (byte_idx < 0 || byte_idx + a->elem_size >= a->back) { return NULL; }
+    return &a->data[byte_idx];
+}
+
+void *pit_arena_alloc_back(pit_arena *a, i64 sz) {
+    i64 next_byte = pit_arena_byte_idx(a, a->next);
+    i64 back_byte = (i64) pit_align_down((uintptr_t) (a->back - sz), sizeof(void *));
+    if (back_byte < next_byte) return NULL;
+    a->back = back_byte;
+    return &a->data[a->back];
+}
diff --git a/pit/src/lexer.c b/pit/src/lexer.c
new file mode 100644
index 0000000..a2b0c7d
--- /dev/null
+++ b/pit/src/lexer.c
@@ -0,0 +1,139 @@
+#include <lcq/pit/utils.h>
+#include <lcq/pit/lexer.h>
+
+const char *PIT_LEX_TOKEN_NAMES[PIT_LEX_TOKEN__SENTINEL] = {
+    /* [PIT_LEX_TOKEN_EOF] = */ "eof",
+    /* [PIT_LEX_TOKEN_LPAREN] = */ "lparen",
+    /* [PIT_LEX_TOKEN_RPAREN] = */ "rparen",
+    /* [PIT_LEX_TOKEN_LSQUARE] = */ "lsquare",
+    /* [PIT_LEX_TOKEN_RSQUARE] = */ "rsquare",
+    /* [PIT_LEX_TOKEN_DOT] = */ "dot",
+    /* [PIT_LEX_TOKEN_QUOTE] = */ "quote",
+    /* [PIT_LEX_TOKEN_INTEGER_LITERAL] = */ "integer_literal",
+    /* [PIT_LEX_TOKEN_STRING_LITERAL] = */ "string_literal",
+    /* [PIT_LEX_TOKEN_SYMBOL] = */ "symbol",
+};
+
+const char *pit_lex_token_name(pit_lex_token t) {
+    return PIT_LEX_TOKEN_NAMES[t];
+}
+
+static bool is_more_input(pit_lexer *st) {
+    return st && st->end < st->len;
+}
+
+static int is_symchar(int c) {
+    return c != '(' && c != ')' && c != '[' && c != ']' && c != '.' && c != '\'' && c != '"'
+        && pit_libc_ctype_isprint(c)
+        && !pit_libc_ctype_isspace(c);
+}
+
+static int is_hexdigit(int c) {
+    return pit_libc_ctype_isdigit(c) || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F');
+}
+
+static char peek(pit_lexer *st) {
+    if (is_more_input(st)) return st->input[st->end];
+    else return 0;
+}
+
+static char advance(pit_lexer *st) {
+    if (is_more_input(st)) {
+        char ret = st->input[st->end++];
+        if (ret == '\n') {
+            st->line += 1;
+            st->column = 0;
+        } else {
+            st->column += 1;
+        }
+        return ret;
+    }
+    else return 0;
+}
+
+static bool match(pit_lexer *st, int (*f)(int)) {
+    if (f(peek(st))) {
+        advance(st);
+        return true;
+    } else return false;
+}
+
+void pit_lex_bytes(pit_lexer *ret, char *buf, i64 len) {
+    ret->len = len;
+    ret->input = buf;
+    ret->start = 0;
+    ret->end = 0;
+    ret->line = ret->start_line = 1;
+    ret->column = ret->start_column = 0;
+    ret->error = NULL;
+}
+
+pit_lex_token pit_lex_next(pit_lexer *st) {
+restart:
+    st->start = st->end;
+    st->start_line = st->line;
+    st->start_column = st->column;
+    char c = advance(st);
+    switch (c) {
+    case 0: return PIT_LEX_TOKEN_EOF;
+    case ';': while (is_more_input(st) && advance(st) != '\n'); goto restart;
+    case '(': return PIT_LEX_TOKEN_LPAREN;
+    case ')': return PIT_LEX_TOKEN_RPAREN;
+    case '[': return PIT_LEX_TOKEN_LSQUARE;
+    case ']': return PIT_LEX_TOKEN_RSQUARE;
+    case '.': return PIT_LEX_TOKEN_DOT;
+    case '\'': return PIT_LEX_TOKEN_QUOTE;
+    case '"':
+        while (peek(st) != '"') {
+            if (peek(st) == '\\') advance(st); /* skip escaped characters */
+            if (!advance(st)) {
+                st->error = "unterminated string";
+                return PIT_LEX_TOKEN_ERROR;
+            }
+        }
+        advance(st);
+        return PIT_LEX_TOKEN_STRING_LITERAL;
+    default: {
+        if (pit_libc_ctype_isspace(c)) goto restart;
+        pit_lex_token ret = PIT_LEX_TOKEN_INTEGER_LITERAL;
+        int num_idx = 0;
+        bool hex = false;
+        bool leading_dash = false;
+        bool zero_prefix = false;
+        if (!is_symchar(c)) {
+            st->error = "unknown character";
+            return PIT_LEX_TOKEN_ERROR;
+        } else {
+            do {
+                leading_dash = false;
+                switch (num_idx) {
+                case 0:
+                    if (c == '0') zero_prefix = true;
+                    else if (c == '-') { leading_dash = true; continue; }
+                    break;
+                case 1:
+                    if (zero_prefix) {
+                        if (c == 'x') { hex = true; continue; }
+                        else if (c == 'o' || c == 'b') continue;
+                    }
+                    break;
+                }
+                if (!(pit_libc_ctype_isdigit(c) || (hex && is_hexdigit(c)))) ret = PIT_LEX_TOKEN_SYMBOL;
+                ++num_idx;
+            } while (c = peek(st), match(st, is_symchar));
+        }
+        if (leading_dash) return PIT_LEX_TOKEN_SYMBOL;
+        return ret;
+    }
+    }
+}
+
+void pit_lex_cstr(pit_lexer *ret, char *buf) {
+    ret->input = buf;
+    ret->len = (i64) pit_libc_string_strlen(buf);
+    ret->start = 0;
+    ret->end = 0;
+    ret->line = ret->start_line = 1;
+    ret->column = ret->start_column = 0;
+    ret->error = NULL;
+}
diff --git a/pit/src/library.c b/pit/src/library.c
new file mode 100644
index 0000000..b6b8b42
--- /dev/null
+++ b/pit/src/library.c
@@ -0,0 +1,910 @@
+#include <lcq/pit/vec.h>
+#include <lcq/pit/lexer.h>
+#include <lcq/pit/parser.h>
+#include <lcq/pit/runtime.h>
+#include <lcq/pit/library.h>
+
+static pit_value impl_sf_quote(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_runtime_eval_program_push_literal(rt, rt->program, pit_value_cons_car(rt, args));
+    return PIT_NIL;
+}
+static pit_value impl_sf_if(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value c = pit_value_cons_car(rt, args);
+    if (pit_eval(rt, c) != PIT_NIL) {
+        if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons_car(rt, pit_value_cons_cdr(rt, args))) < 0)
+            pit_error(rt, "in special form \"if\": evaluation stack overflow");
+    } else {
+        if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons_car(rt, pit_value_cons_cdr(rt, pit_value_cons_cdr(rt, args)))) < 0)
+            pit_error(rt, "in special form \"if\": evaluation stack overflow");
+    }
+    return PIT_NIL;
+}
+static pit_value impl_sf_cond(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    while (args != PIT_NIL) {
+        pit_value clause = pit_value_cons_car(rt, args);
+        pit_value cond = pit_value_cons_car(rt, clause);
+        if (pit_eval(rt, cond) != PIT_NIL) {
+            if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons(rt, pit_symtab_intern_cstr(rt, "progn"), pit_value_cons_cdr(rt, clause))) < 0)
+                pit_error(rt, "in special form \"cond\": evaluation stack overflow");
+            return PIT_NIL;
+        }
+        args = pit_value_cons_cdr(rt, args);
+    }
+    if (pit_vec_push(pit_value)(rt->expr_stack, PIT_NIL) < 0)
+        pit_error(rt, "in special form \"cond\": evaluation stack overflow");
+    return PIT_NIL;
+}
+static pit_value impl_sf_progn(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value bodyforms = args;
+    pit_value final = PIT_NIL;
+    while (bodyforms != PIT_NIL) {
+        final = pit_eval(rt, pit_value_cons_car(rt, bodyforms));
+        bodyforms = pit_value_cons_cdr(rt, bodyforms);
+    }
+    pit_runtime_eval_program_push_literal(rt, rt->program, final);
+    return PIT_NIL;
+}
+static pit_value impl_sf_or(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value bodyforms = args;
+    pit_value final = PIT_NIL;
+    while (bodyforms != PIT_NIL) {
+        final = pit_eval(rt, pit_value_cons_car(rt, bodyforms));
+        if (final != PIT_NIL) break;
+        bodyforms = pit_value_cons_cdr(rt, bodyforms);
+    }
+    pit_runtime_eval_program_push_literal(rt, rt->program, final);
+    return PIT_NIL;
+}
+static pit_value impl_sf_lambda(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value as = pit_value_cons_car(rt, args);
+    pit_value body = pit_value_cons_cdr(rt, args);
+    pit_runtime_eval_program_push_literal(rt, rt->program, pit_value_func_lambda(rt, as, body));
+    return PIT_NIL;
+}
+static pit_value impl_m_defun(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value nm = pit_value_cons_car(rt, args);
+    pit_value as = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_value body = pit_value_cons_cdr(rt, pit_value_cons_cdr(rt, args));
+    return pit_value_list(rt, 3,
+        pit_symtab_intern_cstr(rt, "fset!"),
+        pit_value_list(rt, 2, pit_symtab_intern_cstr(rt, "quote"), nm),
+        pit_value_cons(rt, pit_symtab_intern_cstr(rt, "lambda"), pit_value_cons(rt, as, body))
+    );
+}
+static pit_value impl_m_defmacro(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value nm = pit_value_cons_car(rt, args);
+    return pit_value_list(rt, 3,
+        pit_symtab_intern_cstr(rt, "progn"),
+        pit_value_cons(rt, pit_symtab_intern_cstr(rt, "defun!"), args),
+        pit_value_list(rt, 2, pit_symtab_intern_cstr(rt, "set-symbol-macro!"), nm)
+    );
+}
+static pit_value impl_m_defstruct(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value ret = PIT_NIL;
+    pit_value df = PIT_NIL;
+    pit_value aargs = PIT_NIL;
+    char nm_str[128];
+    char field_str[128];
+    char buf[512];
+    pit_value nm = pit_value_cons_car(rt, args);
+    pit_value fields = pit_value_cons_cdr(rt, args);
+    i64 field_idx = 0;
+    i64 nm_len = pit_value_bytes_copy(rt, pit_symtab_symbol_name(rt, nm), (u8 *) nm_str, sizeof(nm_str) - 1);
+    if (nm_len < 0) return PIT_NIL;
+    nm_str[nm_len] = 0;
+    /* constructor */
+    pit_libc_string_snprintf(buf, sizeof(buf), ":%s", nm_str);
+    aargs = pit_value_cons(rt, pit_symtab_intern_cstr(rt, buf), pit_value_cons(rt, pit_symtab_intern_cstr(rt, "array"), PIT_NIL));
+    fields = pit_value_cons_cdr(rt, args);
+    while (fields != PIT_NIL) {
+        i64 field_len = pit_value_bytes_copy(rt,
+            pit_symtab_symbol_name(rt, pit_value_cons_car(rt, fields)),
+            (u8 *) field_str, sizeof(field_str) - 1
+        );
+        if (field_len < 0) return PIT_NIL;
+        field_str[field_len] = 0;
+        pit_libc_string_snprintf(buf, sizeof(buf), ":%s", field_str);
+        aargs = pit_value_cons(rt,
+            pit_value_list(rt, 3, pit_symtab_intern_cstr(rt, "plist/get"), pit_symtab_intern_cstr(rt, buf), pit_symtab_intern_cstr(rt, "kwargs")),
+            aargs
+        );
+        fields = pit_value_cons_cdr(rt, fields);
+    }
+    pit_libc_string_snprintf(buf, sizeof(buf), "%s/new", nm_str);
+    df = pit_value_list(rt, 4,
+        pit_symtab_intern_cstr(rt, "defun!"),
+        pit_symtab_intern_cstr(rt, buf),
+        pit_value_list(rt, 2, pit_symtab_intern_cstr(rt, "&"), pit_symtab_intern_cstr(rt, "kwargs")),
+        pit_value_list_reverse(rt, aargs)
+    );
+    ret = pit_value_cons(rt, df, ret);
+    /* getters and setters */
+    fields = pit_value_cons_cdr(rt, args);
+    field_idx = 0;
+    while (fields != PIT_NIL) {
+        i64 field_len = pit_value_bytes_copy(rt,
+            pit_symtab_symbol_name(rt, pit_value_cons_car(rt, fields)),
+            (u8 *) field_str, sizeof(field_str) - 1
+        );
+        if (field_len < 0) return PIT_NIL;
+        field_str[field_len] = 0;
+        /* getter */
+        pit_libc_string_snprintf(buf, sizeof(buf), "%s/get-%s", nm_str, field_str);
+        df = pit_value_list(rt, 4,
+            pit_symtab_intern_cstr(rt, "defun!"),
+            pit_symtab_intern_cstr(rt, buf),
+            pit_value_list(rt, 1, pit_symtab_intern_cstr(rt, "v")),
+            pit_value_list(rt, 3,
+                pit_symtab_intern_cstr(rt, "array/get"),
+                pit_value_integer_new(rt, field_idx + 1),
+                pit_symtab_intern_cstr(rt, "v")
+            )
+        );
+        ret = pit_value_cons(rt, df, ret);
+        /* setter */
+        pit_libc_string_snprintf(buf, sizeof(buf), "%s/set-%s!", nm_str, field_str);
+        df = pit_value_list(rt, 4,
+            pit_symtab_intern_cstr(rt, "defun!"),
+            pit_symtab_intern_cstr(rt, buf),
+            pit_value_list(rt, 2, pit_symtab_intern_cstr(rt, "v"), pit_symtab_intern_cstr(rt, "x")),
+            pit_value_list(rt, 4,
+                pit_symtab_intern_cstr(rt, "array/set!"),
+                pit_value_integer_new(rt, field_idx + 1),
+                pit_symtab_intern_cstr(rt, "x"),
+                pit_symtab_intern_cstr(rt, "v")
+            )
+        );
+        ret = pit_value_cons(rt, df, ret);
+        fields = pit_value_cons_cdr(rt, fields);
+        field_idx += 1;
+    }
+    // (defstruct foo x y z)
+    // (defun foo/new (kwargs) ...)
+    // (defun foo/get-x (f) ...)
+    // (defun foo/set-x! (f v) ...)
+    // pit_trace(rt, ret);
+    return pit_value_cons(rt, pit_symtab_intern_cstr(rt, "progn"), ret);
+}
+static pit_value impl_m_let(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value lparams = PIT_NIL;
+    pit_value largs = PIT_NIL;
+    pit_value binds = pit_value_cons_car(rt, args);
+    pit_value bodyforms = pit_value_cons_cdr(rt, args);
+    pit_value lambda, application;
+    while (binds != PIT_NIL) {
+        pit_value bind = pit_value_cons_car(rt, binds);
+        pit_value sym = pit_value_cons_car(rt, bind);
+        pit_value expr = pit_value_cons_car(rt, pit_value_cons_cdr(rt, bind));
+        lparams = pit_value_cons(rt, sym, lparams);
+        largs = pit_value_cons(rt, expr, largs);
+        binds = pit_value_cons_cdr(rt, binds);
+    }
+    lambda = pit_value_cons(rt, pit_symtab_intern_cstr(rt, "lambda"), pit_value_cons(rt, lparams, bodyforms));
+    application = pit_value_cons(rt, lambda, largs);
+    return application;
+}
+static pit_value impl_m_and(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value ret = PIT_NIL;
+    args = pit_value_list_reverse(rt, args);
+    if (args != PIT_NIL) {
+        ret = pit_value_cons_car(rt, args);
+        args = pit_value_cons_cdr(rt, args);
+    }
+    while (args != PIT_NIL) {
+        ret = pit_value_list(rt, 3, pit_symtab_intern_cstr(rt, "if"), pit_value_cons_car(rt, args), ret, PIT_NIL);
+        args = pit_value_cons_cdr(rt, args);
+    }
+    return ret;
+}
+static pit_value impl_m_setq(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value sym = pit_value_cons_car(rt, args);
+    pit_value v = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    return pit_value_list(rt, 3,
+        pit_symtab_intern_cstr(rt, "set!"),
+        pit_value_list(rt, 2, pit_symtab_intern_cstr(rt, "quote"), sym),
+        v
+    );
+}
+
+// (case x (y 'foo) (z 'bar))
+// (cond ((eq x 'y) 'foo) ((eq x 'z) 'bar))
+static pit_value impl_m_case(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value x = pit_value_cons_car(rt, args);
+    pit_value cases = pit_value_cons_cdr(rt, args);
+    pit_value clauses = PIT_NIL;
+    pit_value xvar = pit_symtab_intern_cstr(rt, "(internal case)");
+    while (cases != PIT_NIL) {
+        pit_value c = pit_value_cons_car(rt, cases);
+        clauses = pit_value_cons(rt,
+            pit_value_list(rt, 2,
+                pit_value_list(rt, 3, pit_symtab_intern_cstr(rt, "equal?"),
+                    xvar,
+                    pit_value_list(rt, 2, pit_symtab_intern_cstr(rt, "quote"), pit_value_cons_car(rt, c))
+                ),
+                pit_value_cons_car(rt, pit_value_cons_cdr(rt, c))
+            ),
+            clauses
+        );
+        cases = pit_value_cons_cdr(rt, cases);
+    }
+    return pit_value_list(rt, 3,
+        pit_symtab_intern_cstr(rt, "let"),
+        pit_value_list(rt, 1, pit_value_list(rt, 2, xvar, x)),
+        pit_value_cons(rt, pit_symtab_intern_cstr(rt, "cond"), pit_value_list_reverse(rt, clauses))
+    );
+}
+static pit_value impl_set(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value sym = pit_value_cons_car(rt, args);
+    pit_value v = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_symtab_set(rt, sym, v);
+    return v;
+}
+static pit_value impl_fset(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value sym = pit_value_cons_car(rt, args);
+    pit_value v = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_symtab_fset(rt, sym, v);
+    return v;
+}
+static pit_value impl_symbol_mark_macro(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value sym = pit_value_cons_car(rt, args);
+    pit_symtab_symbol_mark_macro(rt, sym);
+    return PIT_NIL;
+}
+static pit_value impl_funcall(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value f = pit_value_cons_car(rt, args);
+    return pit_value_apply(rt, f, pit_value_cons_cdr(rt, args));
+}
+static pit_value impl_apply(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value f = pit_value_cons_car(rt, args);
+    pit_value xs = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    return pit_value_apply(rt, f, xs);
+}
+static pit_value impl_error(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    rt->error = PIT_T;
+    rt->error = pit_value_cons_car(rt, args);
+    rt->error_line = rt->source_line;
+    rt->error_column = rt->source_column;
+    return PIT_NIL;
+}
+static pit_value impl_eval(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return pit_eval(rt, pit_value_cons_car(rt, args));
+}
+static pit_value impl_eq_p(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value x = pit_value_cons_car(rt, args);
+    pit_value y = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    return pit_value_bool_new(rt, pit_value_eq(x, y));
+}
+static pit_value impl_equal_p(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value x = pit_value_cons_car(rt, args);
+    pit_value y = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    return pit_value_bool_new(rt, pit_value_equal(rt, x, y));
+}
+static pit_value impl_integer_p(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return pit_value_bool_new(rt, pit_value_is_integer(rt, pit_value_cons_car(rt, args)));
+}
+static pit_value impl_double_p(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return pit_value_bool_new(rt, pit_value_is_double(rt, pit_value_cons_car(rt, args)));
+}
+static pit_value impl_symbol_p(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return pit_value_bool_new(rt, pit_value_is_symbol(rt, pit_value_cons_car(rt, args)));
+}
+static pit_value impl_cons_p(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return pit_value_bool_new(rt, pit_value_is_cons(rt, pit_value_cons_car(rt, args)));
+}
+static pit_value impl_array_p(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return pit_value_bool_new(rt, pit_value_is_array(rt, pit_value_cons_car(rt, args)));
+}
+static pit_value impl_bytes_p(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return pit_value_bool_new(rt, pit_value_is_bytes(rt, pit_value_cons_car(rt, args)));
+}
+static pit_value impl_function_p(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value a = pit_value_cons_car(rt, args);
+    bool b = (pit_value_is_symbol(rt, a) && pit_symtab_fget(rt, a) != PIT_NIL)
+        || pit_value_is_func(rt, a)
+        || pit_value_is_nativefunc(rt, a);
+    return pit_value_bool_new(rt, b);
+}
+static pit_value impl_cons(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return pit_value_cons(rt, pit_value_cons_car(rt, args), pit_value_cons_car(rt, pit_value_cons_cdr(rt, args)));
+}
+static pit_value impl_car(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return pit_value_cons_car(rt, pit_value_cons_car(rt, args));
+}
+static pit_value impl_cdr(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return pit_value_cons_cdr(rt, pit_value_cons_car(rt, args));
+}
+static pit_value impl_setcar(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value v = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_value_cons_setcar(rt, pit_value_cons_car(rt, args), v);
+    return v;
+}
+static pit_value impl_setcdr(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value v = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_value_cons_setcdr(rt, pit_value_cons_car(rt, args), v);
+    return v;
+}
+static pit_value impl_list(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    (void) rt;
+    return args;
+}
+static pit_value impl_list_nth(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 n = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    pit_value xs = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    while (xs != PIT_NIL && n-- > 0) {
+        xs = pit_value_cons_cdr(rt, xs);
+    }
+    return pit_value_cons_car(rt, xs);
+}
+static pit_value impl_list_iota(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 n = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    pit_value ret = PIT_NIL;
+    while (n > 0) {
+        ret = pit_value_cons(rt, pit_value_integer_new(rt, --n), ret);
+    }
+    return ret;
+}
+static pit_value impl_list_len(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value arr = pit_value_cons_car(rt, args);
+    return pit_value_integer_new(rt, pit_value_list_len(rt, arr));
+}
+static pit_value impl_list_reverse(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return pit_value_list_reverse(rt, pit_value_cons_car(rt, args));
+}
+static pit_value impl_list_uniq(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value xs = pit_value_cons_car(rt, args);
+    pit_value ret = PIT_NIL;
+    while (xs != PIT_NIL) {
+        pit_value x = pit_value_cons_car(rt, xs);
+        if (pit_value_list_contains_equal(rt, x, ret) == PIT_NIL) {
+            ret = pit_value_cons(rt, x, ret);
+        }
+        xs = pit_value_cons_cdr(rt, xs);
+    }
+    return pit_value_list_reverse(rt, ret);
+}
+static pit_value impl_list_append(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    args = pit_value_list_reverse(rt, args);
+    pit_value ret = pit_value_cons_car(rt, args);
+    pit_value ls = pit_value_cons_cdr(rt, args);
+    while (ls != PIT_NIL) {
+        pit_value xs = pit_value_list_reverse(rt, pit_value_cons_car(rt, ls));
+        while (xs != PIT_NIL) {
+            ret = pit_value_cons(rt, pit_value_cons_car(rt, xs), ret);
+            xs = pit_value_cons_cdr(rt, xs);
+        }
+        ls = pit_value_cons_cdr(rt, ls);
+    }
+    return ret;
+}
+static pit_value impl_list_concat(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    return impl_list_append(rt, pit_value_cons_car(rt, args), NULL);
+}
+static pit_value impl_list_take(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 num = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    pit_value arr = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_value ret = PIT_NIL;
+    while (num > 0 && arr != PIT_NIL) {
+        ret = pit_value_cons(rt, pit_value_cons_car(rt, arr), ret);
+        arr = pit_value_cons_cdr(rt, arr);
+        num -= 1;
+    }
+    return pit_value_list_reverse(rt, ret);
+}
+static pit_value impl_list_drop(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 num = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    pit_value arr = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    while (num > 0 && arr != PIT_NIL) {
+        arr = pit_value_cons_cdr(rt, arr);
+        num -= 1;
+    }
+    return arr;
+}
+static pit_value impl_list_map(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value func = pit_value_cons_car(rt, args);
+    pit_value xs = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_value ret = PIT_NIL;
+    while (xs != PIT_NIL) {
+        pit_value y = pit_value_apply(rt, func, pit_value_cons(rt, pit_value_cons_car(rt, xs), PIT_NIL));
+        ret = pit_value_cons(rt, y, ret);
+        xs = pit_value_cons_cdr(rt, xs);
+    }
+    return pit_value_list_reverse(rt, ret);
+}
+static pit_value impl_list_foldl(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value func = pit_value_cons_car(rt, args);
+    pit_value acc = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_value xs = pit_value_cons_car(rt, pit_value_cons_cdr(rt, pit_value_cons_cdr(rt, args)));
+    while (xs != PIT_NIL) {
+        acc = pit_value_apply(rt, func, pit_value_list(rt, 2, pit_value_cons_car(rt, xs), acc));
+        xs = pit_value_cons_cdr(rt, xs);
+    }
+    return acc;
+}
+static pit_value impl_list_filter(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value func = pit_value_cons_car(rt, args);
+    pit_value xs = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_value ret = PIT_NIL;
+    while (xs != PIT_NIL) {
+        pit_value x = pit_value_cons_car(rt, xs);
+        pit_value y = pit_value_apply(rt, func, pit_value_cons(rt, x, PIT_NIL));
+        if (y != PIT_NIL) {
+            ret = pit_value_cons(rt, x, ret);
+        }
+        xs = pit_value_cons_cdr(rt, xs);
+    }
+    return pit_value_list_reverse(rt, ret);
+}
+static pit_value impl_list_find(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value func = pit_value_cons_car(rt, args);
+    pit_value xs = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    while (xs != PIT_NIL) {
+        pit_value x = pit_value_cons_car(rt, xs);
+        pit_value y = pit_value_apply(rt, func, pit_value_cons(rt, x, PIT_NIL));
+        if (y != PIT_NIL) {
+            return x;
+        }
+        xs = pit_value_cons_cdr(rt, xs);
+    }
+    return PIT_NIL;
+}
+static pit_value impl_list_contains_p(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value needle = pit_value_cons_car(rt, args);
+    pit_value haystack = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    while (haystack != PIT_NIL) {
+        if (pit_value_equal(rt, needle, pit_value_cons_car(rt, haystack))) return PIT_T;
+        haystack = pit_value_cons_cdr(rt, haystack);
+    }
+    return PIT_NIL;
+}
+static pit_value impl_list_all_p(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value f = pit_value_cons_car(rt, args);
+    pit_value xs = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    while (xs != PIT_NIL) {
+        pit_value x = pit_value_cons_car(rt, xs);
+        if (pit_value_apply(rt, f, pit_value_cons(rt, x, PIT_NIL)) == PIT_NIL) {
+            return PIT_NIL;
+        }
+        xs = pit_value_cons_cdr(rt, xs);
+    }
+    return PIT_T;
+}
+static pit_value impl_list_zip_with(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value f = pit_value_cons_car(rt, args);
+    pit_value xs = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_value ys = pit_value_cons_car(rt, pit_value_cons_cdr(rt, pit_value_cons_cdr(rt, args)));
+    pit_value ret = PIT_NIL;
+    while (xs != PIT_NIL && ys != PIT_NIL) {
+        pit_value z = pit_value_apply(rt, f, pit_value_list(rt, 2, pit_value_cons_car(rt, xs), pit_value_cons_car(rt, ys)));
+        ret = pit_value_cons(rt, z, ret);
+        xs = pit_value_cons_cdr(rt, xs); ys = pit_value_cons_cdr(rt, ys);
+    }
+    return pit_value_list_reverse(rt, ret);
+}
+static pit_value impl_bytes_len(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value v = pit_value_cons_car(rt, args);
+    if (pit_value_sort(v) != PIT_VALUE_SORT_REF) {
+        pit_error(rt, "value is not a ref");
+        return PIT_NIL;
+    }
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, v));
+    if (!h) { pit_error(rt, "bad ref"); return PIT_NIL; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_BYTES) { pit_error(rt, "ref is not bytes"); return PIT_NIL; }
+    return pit_value_integer_new(rt, h->in.bytes.len);
+}
+static pit_value impl_bytes_range(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 start = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    i64 end = pit_value_as_integer(rt, pit_value_cons_car(rt, pit_value_cons_cdr(rt, args)));
+    pit_value v = pit_value_cons_car(rt, pit_value_cons_cdr(rt, pit_value_cons_cdr(rt, args)));
+    if (pit_value_sort(v) != PIT_VALUE_SORT_REF) {
+        pit_error(rt, "value is not a ref");
+        return PIT_NIL;
+    }
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, v));
+    if (!h) { pit_error(rt, "bad ref"); return PIT_NIL; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_BYTES) { pit_error(rt, "ref is not bytes"); return PIT_NIL; }
+    if (start < 0 || start >= h->in.bytes.len) {
+        pit_error(rt, "bytes range start index out of bounds: %d", start);
+        return PIT_NIL;
+    }
+    if (end < start || end < 0 || end > h->in.bytes.len) {
+        pit_error(rt, "bytes range end index out of bounds: %d", end);
+        return PIT_NIL;
+    }
+    return pit_value_bytes_new(rt, h->in.bytes.data + start, end - start);
+}
+static pit_value impl_array(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 len = pit_value_list_len(rt, args);
+    pit_value ret = pit_value_array_new(rt, len);
+    i64 idx = 0;
+    while (args != PIT_NIL) {
+        pit_value_array_set(rt, ret, idx++, pit_value_cons_car(rt, args));
+        args = pit_value_cons_cdr(rt, args);
+    }
+    return ret;
+}
+static pit_value impl_array_to_list(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value arr = pit_value_cons_car(rt, args);
+    i64 ilen = pit_value_array_len(rt, arr);
+    pit_value ret = PIT_NIL;
+    i64 i = 0;
+    for (; i < ilen; ++i) {
+        ret = pit_value_cons(rt, pit_value_array_get(rt, arr, i), ret);
+    }
+    return pit_value_list_reverse(rt, ret);
+}
+static pit_value impl_array_from_list(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 i = 0;
+    pit_value xs = pit_value_cons_car(rt, args);
+    i64 ilen = pit_value_list_len(rt, xs);
+    pit_value ret = pit_value_array_new(rt, ilen);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to deref heavy value for array"); return PIT_NIL; }
+    while (xs != PIT_NIL) {
+        h->in.array.data[i] = pit_value_cons_car(rt, xs);
+        xs = pit_value_cons_cdr(rt, xs);
+        i += 1;
+    }
+    return ret;
+}
+static pit_value impl_array_repeat(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 i = 0;
+    pit_value v = pit_value_cons_car(rt, args);
+    pit_value len = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    i64 ilen = pit_value_as_integer(rt, len);
+    pit_value ret = pit_value_array_new(rt, ilen);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to deref heavy value for array"); return PIT_NIL; }
+    for (; i < ilen; ++i) {
+        h->in.array.data[i] = v;
+    }
+    return ret;
+}
+static pit_value impl_array_len(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value arr = pit_value_cons_car(rt, args);
+    return pit_value_integer_new(rt, pit_value_array_len(rt, arr));
+}
+static pit_value impl_array_get(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value idx = pit_value_cons_car(rt, args);
+    pit_value arr = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    return pit_value_array_get(rt, arr, pit_value_as_integer(rt, idx));
+}
+static pit_value impl_array_set(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value idx = pit_value_cons_car(rt, args);
+    pit_value v = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_value arr = pit_value_cons_car(rt, pit_value_cons_cdr(rt, pit_value_cons_cdr(rt, args)));
+    return pit_value_array_set(rt, arr, pit_value_as_integer(rt, idx), v);
+}
+static pit_value impl_array_map(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value func = pit_value_cons_car(rt, args);
+    pit_value arr = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    i64 len = pit_value_array_len(rt, arr);
+    pit_value ret = pit_value_array_new(rt, len);
+    i64 i = 0;
+    for (i = 0; i < len; ++i) {
+        pit_value y = pit_value_apply(rt, func, pit_value_cons(rt, pit_value_array_get(rt, arr, i), PIT_NIL));
+        pit_value_array_set(rt, ret, i, y);
+    }
+    return ret;
+}
+static pit_value impl_array_map_mut(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value func = pit_value_cons_car(rt, args);
+    pit_value arr = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    i64 len = pit_value_array_len(rt, arr);
+    i64 i = 0;
+    for (i = 0; i < len; ++i) {
+        pit_value y = pit_value_apply(rt, func, pit_value_cons(rt, pit_value_array_get(rt, arr, i), PIT_NIL));
+        pit_value_array_set(rt, arr, i, y);
+    }
+    return arr;
+}
+static pit_value impl_abs(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 x = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    if (x < 0) return pit_value_integer_new(rt, -x);
+    return pit_value_integer_new(rt, x);
+}
+static pit_value impl_add(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 total = 0;
+    while (args != PIT_NIL) {
+        total += pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+        args = pit_value_cons_cdr(rt, args);
+    }
+    return pit_value_integer_new(rt, total);
+}
+static pit_value impl_sub(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 total = 0;
+    while (args != PIT_NIL) {
+        total -= pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+        args = pit_value_cons_cdr(rt, args);
+    }
+    return pit_value_integer_new(rt, total);
+}
+static pit_value impl_mul(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 total = 1;
+    while (args != PIT_NIL) {
+        total *= pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+        args = pit_value_cons_cdr(rt, args);
+    }
+    return pit_value_integer_new(rt, total);
+}
+static pit_value impl_div(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 total = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    args = pit_value_cons_cdr(rt, args);
+    while (args != PIT_NIL) {
+        i64 denom = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+        if (denom == 0) {
+            pit_error(rt, "divide by zero");
+            return PIT_NIL;
+        }
+        total /= denom;
+        args = pit_value_cons_cdr(rt, args);
+    }
+    return pit_value_integer_new(rt, total);
+}
+static pit_value impl_not(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    if (pit_value_cons_car(rt, args) == PIT_NIL) {
+        return PIT_T;
+    } else {
+        return PIT_NIL;
+    }
+}
+static pit_value impl_lt(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 x = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    i64 y = pit_value_as_integer(rt, pit_value_cons_car(rt, pit_value_cons_cdr(rt, args)));
+    return pit_value_bool_new(rt, x < y);
+}
+static pit_value impl_gt(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 x = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    i64 y = pit_value_as_integer(rt, pit_value_cons_car(rt, pit_value_cons_cdr(rt, args)));
+    return pit_value_bool_new(rt, x > y);
+}
+static pit_value impl_le(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 x = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    i64 y = pit_value_as_integer(rt, pit_value_cons_car(rt, pit_value_cons_cdr(rt, args)));
+    return pit_value_bool_new(rt, x <= y);
+}
+static pit_value impl_ge(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 x = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    i64 y = pit_value_as_integer(rt, pit_value_cons_car(rt, pit_value_cons_cdr(rt, args)));
+    return pit_value_bool_new(rt, x >= y);
+}
+static pit_value impl_bitwise_and(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 total = -1;
+    while (args != PIT_NIL) {
+        total &= pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+        args = pit_value_cons_cdr(rt, args);
+    }
+    return pit_value_integer_new(rt, total);
+}
+static pit_value impl_bitwise_or(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 total = 0;
+    while (args != PIT_NIL) {
+        total |= pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+        args = pit_value_cons_cdr(rt, args);
+    }
+    return pit_value_integer_new(rt, total);
+}
+static pit_value impl_bitwise_xor(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 total = 0;
+    while (args != PIT_NIL) {
+        total ^= pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+        args = pit_value_cons_cdr(rt, args);
+    }
+    return pit_value_integer_new(rt, total);
+}
+static pit_value impl_bitwise_not(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 x = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    return pit_value_integer_new(rt, ~x);
+}
+static pit_value impl_bitwise_lshift(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 val = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    i64 shift = pit_value_as_integer(rt, pit_value_cons_car(rt, pit_value_cons_cdr(rt, args)));
+    return pit_value_integer_new(rt, val << shift);
+}
+static pit_value impl_bitwise_rshift(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    i64 val = pit_value_as_integer(rt, pit_value_cons_car(rt, args));
+    i64 shift = pit_value_as_integer(rt, pit_value_cons_car(rt, pit_value_cons_cdr(rt, args)));
+    if (shift >= 64) val = 0;
+    else val >>= shift;
+    return pit_value_integer_new(rt, val);
+}
+void pit_install_library_essential(pit_runtime *rt) {
+    /* special forms */
+    pit_symtab_sfset(rt, pit_symtab_intern_cstr(rt, "quote"), pit_value_nativefunc_new(rt, impl_sf_quote));
+    pit_symtab_sfset(rt, pit_symtab_intern_cstr(rt, "if"), pit_value_nativefunc_new(rt, impl_sf_if));
+    pit_symtab_sfset(rt, pit_symtab_intern_cstr(rt, "cond"), pit_value_nativefunc_new(rt, impl_sf_cond));
+    pit_symtab_sfset(rt, pit_symtab_intern_cstr(rt, "progn"), pit_value_nativefunc_new(rt, impl_sf_progn));
+    pit_symtab_sfset(rt, pit_symtab_intern_cstr(rt, "or"), pit_value_nativefunc_new(rt, impl_sf_or));
+    pit_symtab_sfset(rt, pit_symtab_intern_cstr(rt, "lambda"), pit_value_nativefunc_new(rt, impl_sf_lambda));
+    /* macros */
+    pit_symtab_mset(rt, pit_symtab_intern_cstr(rt, "defun!"), pit_value_nativefunc_new(rt, impl_m_defun));
+    pit_symtab_mset(rt, pit_symtab_intern_cstr(rt, "defmacro!"), pit_value_nativefunc_new(rt, impl_m_defmacro));
+    pit_symtab_mset(rt, pit_symtab_intern_cstr(rt, "defstruct!"), pit_value_nativefunc_new(rt, impl_m_defstruct));
+    pit_symtab_mset(rt, pit_symtab_intern_cstr(rt, "let"), pit_value_nativefunc_new(rt, impl_m_let));
+    pit_symtab_mset(rt, pit_symtab_intern_cstr(rt, "and"), pit_value_nativefunc_new(rt, impl_m_and));
+    pit_symtab_mset(rt, pit_symtab_intern_cstr(rt, "setq!"), pit_value_nativefunc_new(rt, impl_m_setq));
+    pit_symtab_mset(rt, pit_symtab_intern_cstr(rt, "case"), pit_value_nativefunc_new(rt, impl_m_case));
+    /* error */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "error!"), pit_value_nativefunc_new(rt, impl_error));
+    /* eval */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "eval!"), pit_value_nativefunc_new(rt, impl_eval));
+    /* predicates */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "eq?"), pit_value_nativefunc_new(rt, impl_eq_p));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "equal?"), pit_value_nativefunc_new(rt, impl_equal_p));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "integer?"), pit_value_nativefunc_new(rt, impl_integer_p));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "double?"), pit_value_nativefunc_new(rt, impl_double_p));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "symbol?"), pit_value_nativefunc_new(rt, impl_symbol_p));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "cons?"), pit_value_nativefunc_new(rt, impl_cons_p));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "array?"), pit_value_nativefunc_new(rt, impl_array_p));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bytes?"), pit_value_nativefunc_new(rt, impl_bytes_p));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "function?"), pit_value_nativefunc_new(rt, impl_function_p));
+    /* symbols */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "set!"), pit_value_nativefunc_new(rt, impl_set));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "fset!"), pit_value_nativefunc_new(rt, impl_fset));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "symbol-is-macro!"), pit_value_nativefunc_new(rt, impl_symbol_mark_macro));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "funcall"), pit_value_nativefunc_new(rt, impl_funcall));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "apply"), pit_value_nativefunc_new(rt, impl_apply));
+    /* cons cells */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "cons"), pit_value_nativefunc_new(rt, impl_cons));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "car"), pit_value_nativefunc_new(rt, impl_car));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "cdr"), pit_value_nativefunc_new(rt, impl_cdr));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "setcar!"), pit_value_nativefunc_new(rt, impl_setcar));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "setcdr!"), pit_value_nativefunc_new(rt, impl_setcdr));
+    /* cons lists*/
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list"), pit_value_nativefunc_new(rt, impl_list));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/nth"), pit_value_nativefunc_new(rt, impl_list_nth));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/iota"), pit_value_nativefunc_new(rt, impl_list_iota));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/len"), pit_value_nativefunc_new(rt, impl_list_len));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/reverse"), pit_value_nativefunc_new(rt, impl_list_reverse));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/uniq"), pit_value_nativefunc_new(rt, impl_list_uniq));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/append"), pit_value_nativefunc_new(rt, impl_list_append));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/concat"), pit_value_nativefunc_new(rt, impl_list_concat));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/take"), pit_value_nativefunc_new(rt, impl_list_take));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/drop"), pit_value_nativefunc_new(rt, impl_list_drop));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/map"), pit_value_nativefunc_new(rt, impl_list_map));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/foldl"), pit_value_nativefunc_new(rt, impl_list_foldl));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/filter"), pit_value_nativefunc_new(rt, impl_list_filter));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/find"), pit_value_nativefunc_new(rt, impl_list_find));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/contains?"), pit_value_nativefunc_new(rt, impl_list_contains_p));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/all?"), pit_value_nativefunc_new(rt, impl_list_all_p));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "list/zip-with"), pit_value_nativefunc_new(rt, impl_list_zip_with));
+    /* bytestrings */ 
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bytes/len"), pit_value_nativefunc_new(rt, impl_bytes_len));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bytes/range"), pit_value_nativefunc_new(rt, impl_bytes_range));
+    /* array */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "array"), pit_value_nativefunc_new(rt, impl_array));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "array/to-list"), pit_value_nativefunc_new(rt, impl_array_to_list));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "array/from-list"), pit_value_nativefunc_new(rt, impl_array_from_list));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "array/repeat"), pit_value_nativefunc_new(rt, impl_array_repeat));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "array/len"), pit_value_nativefunc_new(rt, impl_array_len));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "array/get"), pit_value_nativefunc_new(rt, impl_array_get));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "array/set!"), pit_value_nativefunc_new(rt, impl_array_set));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "array/map"), pit_value_nativefunc_new(rt, impl_array_map));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "array/map!"), pit_value_nativefunc_new(rt, impl_array_map_mut));
+    /* arithmetic */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "abs"), pit_value_nativefunc_new(rt, impl_abs));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "+"), pit_value_nativefunc_new(rt, impl_add));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "-"), pit_value_nativefunc_new(rt, impl_sub));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "*"), pit_value_nativefunc_new(rt, impl_mul));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "/"), pit_value_nativefunc_new(rt, impl_div));
+    /* booleans */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "not"), pit_value_nativefunc_new(rt, impl_not));
+    /* comparisons */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "<"), pit_value_nativefunc_new(rt, impl_lt));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, ">"), pit_value_nativefunc_new(rt, impl_gt));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "<="), pit_value_nativefunc_new(rt, impl_le));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, ">="), pit_value_nativefunc_new(rt, impl_ge));
+    /* bitwise arithmetic */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bitwise/and"), pit_value_nativefunc_new(rt, impl_bitwise_and));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bitwise/or"), pit_value_nativefunc_new(rt, impl_bitwise_or));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bitwise/xor"), pit_value_nativefunc_new(rt, impl_bitwise_xor));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bitwise/not"), pit_value_nativefunc_new(rt, impl_bitwise_not));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bitwise/lshift"), pit_value_nativefunc_new(rt, impl_bitwise_lshift));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bitwise/rshift"), pit_value_nativefunc_new(rt, impl_bitwise_rshift));
+}
+
+static pit_value impl_plist_get(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value k = pit_value_cons_car(rt, args);
+    pit_value vs = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    return pit_value_list_plist_get(rt, k, vs);
+}
+void pit_install_library_plist(pit_runtime *rt) {
+    /* property lists / keyword arguments */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "plist/get"), pit_value_nativefunc_new(rt, impl_plist_get));
+}
+
+static pit_value impl_alist_get(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value k = pit_value_cons_car(rt, args);
+    pit_value vs = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    while (vs != PIT_NIL) {
+        pit_value v = pit_value_cons_car(rt, vs);
+        if (pit_value_equal(rt, k, pit_value_cons_car(rt, v))) {
+            return pit_value_cons_cdr(rt, v);
+        }
+        vs = pit_value_cons_cdr(rt, vs);
+    }
+    return PIT_NIL;
+}
+void pit_install_library_alist(pit_runtime *rt) {
+    /* association lists */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "alist/get"), pit_value_nativefunc_new(rt, impl_alist_get));
+}
diff --git a/pit/src/main.c b/pit/src/main.c
new file mode 100644
index 0000000..157ad87
--- /dev/null
+++ b/pit/src/main.c
@@ -0,0 +1,24 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <lcq/pit/utils.h>
+#include <lcq/pit/lexer.h>
+#include <lcq/pit/parser.h>
+#include <lcq/pit/runtime.h>
+#include <lcq/pit/library.h>
+
+int main(int argc, char **argv) {
+    i64 sz = 256 * 1024 * 1024;
+    u8 *buf = malloc((size_t) sz);
+    pit_runtime *rt = pit_runtime_new(buf, sz);
+    pit_install_library_essential(rt);
+    pit_install_library_io(rt);
+    pit_install_library_plist(rt);
+    pit_install_library_alist(rt);
+    pit_install_library_bytestring(rt);
+    if (argc < 2) {
+        pit_repl(rt);
+    } else {
+        pit_load_file(rt, argv[1]);
+    }
+}
diff --git a/pit/src/native.c b/pit/src/native.c
new file mode 100644
index 0000000..fbf8efc
--- /dev/null
+++ b/pit/src/native.c
@@ -0,0 +1,307 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <lcq/pit/lexer.h>
+#include <lcq/pit/parser.h>
+#include <lcq/pit/runtime.h>
+#include <lcq/pit/library.h>
+
+i64 pit_lex_file(pit_lexer *ret, char *path) {
+    FILE *f = fopen(path, "r");
+    if (f == NULL) { return -1; }
+    fseek(f, 0, SEEK_END);
+    i64 len = ftell(f);
+    fseek(f, 0, SEEK_SET);
+    char *buf = calloc((size_t) len, sizeof(char));
+    if ((size_t) len != fread(buf, sizeof(char), (size_t) len, f)) {
+        fclose(f);
+        return -1;
+    }
+    fclose(f);
+    pit_lex_bytes(ret, buf, len);
+    return 0;
+}
+
+bool pit_runtime_print_error(pit_runtime *rt) {
+    if (!pit_value_eq(rt->error, PIT_NIL)) {
+        char buf[1024] = {0};
+        for (i64 i = 0; i < rt->backtrace->next; ++i) {
+            pit_annotated_ref *a = pit_vec_get(pit_annotated_ref)(rt->backtrace, i);
+            if (a == NULL) continue;
+            fprintf(stderr, "on line %ld, column %ld\n", a->annotation.line, a->annotation.column);
+        }
+        i64 end = pit_dump(rt, buf, sizeof(buf) - 1, rt->error, false); buf[end] = 0;
+        fprintf(stderr, "error at line %ld, column %ld: %s\n", rt->error_line, rt->error_column, buf);
+        return true;
+    }
+    return false;
+}
+
+void pit_debug_trace_(pit_runtime *rt, char *format, pit_value v) {
+    char buf[1024] = {0};
+    i64 end = pit_dump(rt, buf, sizeof(buf) - 1, v, true);
+    buf[end] = 0;
+    fprintf(stderr, format, buf);
+}
+
+pit_value pit_value_bytes_new_file(pit_runtime *rt, char *path) {
+    if (rt->error != PIT_NIL) return PIT_NIL;
+    FILE *f = fopen(path, "r");
+    if (f == NULL) {
+        pit_error(rt, "failed to open file: %s", path);
+        return PIT_NIL;
+    }
+    fseek(f, 0, SEEK_END);
+    i64 len = ftell(f);
+    fseek(f, 0, SEEK_SET);
+    u8 *dest = pit_arena_alloc_array(rt->heap, len);
+    if (!dest) { pit_error(rt, "failed to allocate bytes"); fclose(f); return PIT_NIL; }
+    if ((size_t) len != fread(dest, sizeof(char), (size_t) len, f)) {
+        fclose(f);
+        pit_error(rt, "failed to read file: %s", path);
+        return PIT_NIL;
+    }
+    fclose(f);
+    pit_value ret = pit_value_ref_heavy_new(rt);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to create new heavy value for bytes"); return PIT_NIL; }
+    h->hsort = PIT_VALUE_HEAVY_SORT_BYTES;
+    h->in.bytes.data = dest;
+    h->in.bytes.len = len;
+    return ret;
+}
+
+static void check_invariants(pit_runtime *rt) {
+    if (rt->expr_stack->next != 0) {
+        pit_error(rt, "leaked expr_stack memory! %ld", rt->expr_stack->next);
+    }
+    if (rt->result_stack->next != 0) {
+        pit_error(rt, "leaked result_stack memory! %ld", rt->result_stack->next);
+    }
+    if (rt->program->next != 0) {
+        pit_error(rt, "leaked program memory! %ld", rt->program->next);
+    }
+}
+pit_value pit_load_file(pit_runtime *rt, char *path) {
+    pit_lexer lex;
+    pit_parser parse;
+    bool eof = false;
+    pit_value p = PIT_NIL;
+    pit_value ret = PIT_NIL;
+    if (pit_lex_file(&lex, path) < 0) {
+        pit_error(rt, "failed to lex file: %s", path);
+        return PIT_NIL;
+    }
+    pit_parser_from_lexer(&parse, &lex);
+    while (p = pit_parse(rt, &parse, &eof), !eof) {
+        check_invariants(rt); if (pit_runtime_print_error(rt)) return PIT_NIL;
+        ret = pit_eval(rt, p);
+        check_invariants(rt); if (pit_runtime_print_error(rt)) return PIT_NIL;
+        pit_gc(rt);
+        check_invariants(rt); if (pit_runtime_print_error(rt)) return PIT_NIL;
+    }
+    check_invariants(rt); if (pit_runtime_print_error(rt)) return PIT_NIL;
+    return ret;
+}
+
+void pit_repl(pit_runtime *rt) {
+    size_t bufcap = 8;
+    char *buf = malloc(bufcap);
+    i64 len = 0;
+    pit_runtime_freeze(rt);
+    check_invariants(rt); if (pit_runtime_print_error(rt)) exit(1);
+    setbuf(stdout, NULL);
+    printf("> ");
+    while ((buf[len++] = (char) getchar()) != EOF) {
+        if (len >= (i64) bufcap) {
+            bufcap *= 2;
+            buf = realloc(buf, bufcap);
+        }
+        pit_value res = PIT_NIL;
+        pit_lexer lex;
+        pit_parser parse;
+        bool eof = false;
+        pit_value p = PIT_NIL;
+        i64 depth = 0;
+        bool lex_error = false;
+        pit_lex_token tok = PIT_LEX_TOKEN_EOF;
+        if (buf[len - 1] != '\n') continue;
+        pit_lex_bytes(&lex, buf, len);
+        while (!lex_error && (tok = pit_lex_next(&lex)) != PIT_LEX_TOKEN_EOF) {
+            switch (tok) {
+            case PIT_LEX_TOKEN_ERROR: lex_error = true; break;
+            case PIT_LEX_TOKEN_LPAREN: depth += 1; break;
+            case PIT_LEX_TOKEN_RPAREN: depth -= 1; break;
+            default: break;
+            }
+        }
+        if (lex_error || depth > 0) continue;
+        buf[len - 1] = 0;
+        pit_lex_bytes(&lex, buf, len);
+        pit_parser_from_lexer(&parse, &lex);
+        while (p = pit_parse(rt, &parse, &eof), !eof) {
+            check_invariants(rt);
+            res = pit_eval(rt, p);
+            check_invariants(rt);
+        }
+        if (pit_runtime_print_error(rt)) {
+            rt->error = PIT_NIL;
+            printf("> ");
+        } else {
+            char dumpbuf[1024] = {0};
+            pit_dump(rt, dumpbuf, sizeof(dumpbuf) - 1, res, true);
+            pit_gc(rt);
+            printf("%s\n> ", dumpbuf);
+        }
+        len = 0;
+    }
+    if (len >= (i64) sizeof(buf)) {
+        fprintf(stderr, "expression exceeded REPL buffer size\n");
+    } else {
+        printf("bye!\n");
+    }
+    free(buf);
+}
+
+static pit_value impl_diagnostics(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    (void) args;
+    fprintf(stderr, "value allocs: %ld\n", rt->heap->next);
+    return PIT_NIL;
+}
+static pit_value impl_print(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value x = pit_value_cons_car(rt, args);
+    char buf[1024] = {0};
+    pit_dump(rt, buf, sizeof(buf), x, true);
+    buf[1023] = 0;
+    puts(buf);
+    return x;
+}
+static pit_value impl_princ(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value x = pit_value_cons_car(rt, args);
+    char buf[1024] = {0};
+    pit_dump(rt, buf, sizeof(buf), x, false);
+    buf[1023] = 0;
+    puts(buf);
+    return x;
+}
+static pit_value impl_load(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value path = pit_value_cons_car(rt, args);
+    char pathbuf[1024] = {0};
+    i64 len = pit_value_bytes_copy(rt, path, (u8 *) pathbuf, sizeof(pathbuf) - 1);
+    if (len < 0) { pit_error(rt, "path was not a string"); return PIT_NIL; }
+    pathbuf[len] = 0;
+    return pit_load_file(rt, pathbuf);
+}
+void pit_install_library_io(pit_runtime *rt) {
+    /* diagnostics */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "diagnostics!"), pit_value_nativefunc_new(rt, impl_diagnostics));
+    /* stream IO */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "print!"), pit_value_nativefunc_new(rt, impl_print));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "princ!"), pit_value_nativefunc_new(rt, impl_princ));
+    /* disk IO */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "load!"), pit_value_nativefunc_new(rt, impl_load));
+}
+
+struct bytestring {
+    i64 len, cap;
+    u8 *data;
+};
+static pit_value impl_bs_new(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    (void) args;
+    i64 cap = 256;
+    struct bytestring *bs = malloc(sizeof(struct bytestring));
+    bs->len = 0;
+    bs->cap = cap;
+    bs->data = calloc((size_t) cap, 1);
+    return pit_value_nativedata_new(rt, pit_symtab_intern_cstr(rt, "bs"), (void *) bs);
+}
+static pit_value impl_bs_delete(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value v = pit_value_cons_car(rt, args);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, v));
+    if (!h) { pit_error(rt, "bad ref"); return PIT_NIL; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_NATIVEDATA) {
+        pit_error(rt, "invalid use of value as bytestring nativedata");
+        return PIT_NIL;
+    }
+    if (!pit_value_eq(h->in.nativedata.tag, pit_symtab_intern_cstr(rt, "bs"))) {
+        pit_error(rt, "native value is not a bytestring");
+        return PIT_NIL;
+    }
+    if (!h->in.nativedata.data) {
+        pit_error(rt, "bytestring was already freed");
+        return PIT_NIL;
+    }
+    struct bytestring *bs = h->in.nativedata.data;
+    if (bs->data) free(bs->data);
+    bs->data = NULL;
+    free(bs);
+    h->in.nativedata.data = NULL;
+    return PIT_T;
+}
+static pit_value impl_bs_grow(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value vsz = pit_value_cons_car(rt, args);
+    pit_value v = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    struct bytestring *bs = pit_value_nativedata_get(rt, pit_symtab_intern_cstr(rt, "bs"), v);
+    if (!bs) return PIT_NIL;
+    i64 sz = pit_value_as_integer(rt, vsz);
+    if (sz > bs->len) {
+        if (sz > bs->cap) {
+            while (bs->cap < sz) bs->cap <<= 1;
+            bs->data = realloc(bs->data, (size_t) bs->cap);
+        }
+        bs->len = sz;
+    }
+    return v;
+}
+static pit_value impl_bs_spit(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value path = pit_value_cons_car(rt, args);
+    char pathbuf[1024] = {0};
+    i64 len = pit_value_bytes_copy(rt, path, (u8 *) pathbuf, sizeof(pathbuf) - 1);
+    if (len < 0) { pit_error(rt, "path was not a string"); return PIT_NIL; }
+    pathbuf[len] = 0;
+    pit_value v = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    struct bytestring *bs = pit_value_nativedata_get(rt, pit_symtab_intern_cstr(rt, "bs"), v);
+    if (!bs) return PIT_NIL;
+    FILE *f = fopen(pathbuf, "w+");
+    if (!f) { pit_error(rt, "failed to open file: %s", pathbuf); return PIT_NIL; }
+    size_t written = fwrite(bs->data, 1, (size_t) bs->len, f);
+    fclose(f);
+    if (written != (size_t) bs->len) {
+        pit_error(rt, "failed to write bytestring to file: %s", pathbuf);
+        return PIT_NIL;
+    }
+    return v;
+}
+static pit_value impl_bs_write8(pit_runtime *rt, pit_value args, void *data) {
+    (void) data;
+    pit_value v = pit_value_cons_car(rt, args);
+    pit_value vidx = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+    pit_value vx = pit_value_cons_car(rt, pit_value_cons_cdr(rt, pit_value_cons_cdr(rt, args)));
+    struct bytestring *bs = pit_value_nativedata_get(rt, pit_symtab_intern_cstr(rt, "bs"), v);
+    if (!bs) return PIT_NIL;
+    i64 idx = pit_value_as_integer(rt, vidx);
+    u8 x = (u8) pit_value_as_integer(rt, vx);
+    if (idx >= bs->len) {
+        pit_error(rt, "index %d out of bounds in bytestring (length %d)", idx, bs->len);
+        return PIT_NIL;
+    }
+    bs->data[idx] = x;
+    return v;
+}
+void pit_install_library_bytestring(pit_runtime *rt) {
+    /* bytestrings */
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bs/new!"), pit_value_nativefunc_new(rt, impl_bs_new));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bs/delete!"), pit_value_nativefunc_new(rt, impl_bs_delete));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bs/grow!"), pit_value_nativefunc_new(rt, impl_bs_grow));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bs/spit!"), pit_value_nativefunc_new(rt, impl_bs_spit));
+    pit_symtab_fset(rt, pit_symtab_intern_cstr(rt, "bs/write8!"), pit_value_nativefunc_new(rt, impl_bs_write8));
+}
diff --git a/pit/src/parser.c b/pit/src/parser.c
new file mode 100644
index 0000000..9c575cb
--- /dev/null
+++ b/pit/src/parser.c
@@ -0,0 +1,177 @@
+#include <lcq/pit/utils.h>
+#include <lcq/pit/lexer.h>
+#include <lcq/pit/parser.h>
+#include <lcq/pit/runtime.h>
+
+static pit_lex_token peek(pit_parser *st) {
+    if (!st) return PIT_LEX_TOKEN_ERROR;
+    return st->next.token;
+}
+
+static pit_lex_token advance(pit_parser *st) {
+    if (!st) return PIT_LEX_TOKEN_ERROR;
+    st->cur = st->next;
+    st->next.token = pit_lex_next(st->lexer);
+    st->next.start = st->lexer->start;
+    st->next.end = st->lexer->end;
+    st->next.line = st->lexer->start_line;
+    st->next.column = st->lexer->start_column;
+    return st->cur.token;
+}
+
+static bool match(pit_parser *st, pit_lex_token t) {
+    if (peek(st) == t) {
+        advance(st);
+        return true;
+    } else return false;
+}
+
+static void get_token_string(pit_parser *st, char *buf, i64 len) {
+    i64 diff = st->cur.end - st->cur.start;
+    i64 tlen = diff >= len ? len - 1 : diff;
+    pit_libc_string_memcpy((u8 *) buf, (u8 *) st->lexer->input + st->cur.start, (size_t) tlen);
+    buf[tlen] = 0;
+}
+
+static i64 digit_value(char c) {
+    if (c >= '0' && c <= '9') {
+        return c - '0';
+    } else if (c >= 'a' && c <= 'f') {
+        return c - 'a' + 10;
+    } else if (c >= 'A' && c <= 'F') {
+        return c - 'A' + 10;
+    } else {
+        return 0;
+    }
+}
+
+void pit_parser_from_lexer(pit_parser *ret, pit_lexer *lex) {
+    ret->lexer = lex;
+    ret->cur.token = ret->next.token = PIT_LEX_TOKEN_ERROR;
+    ret->cur.start = ret->next.start = 0;
+    ret->cur.end = ret->next.end = 0;
+    ret->cur.line = ret->next.line = -1;
+    ret->cur.column = ret->next.column = -1;
+    advance(ret);
+}
+
+/* parse a single expression */
+pit_value pit_parse(pit_runtime *rt, pit_parser *st, bool *eof) {
+    if (rt == NULL || st == NULL) return PIT_NIL;
+    pit_lex_token t = advance(st);
+    rt->source_line = st->cur.line;
+    rt->source_column = st->cur.column;
+    switch (t) {
+    case PIT_LEX_TOKEN_ERROR:
+        pit_error(rt, "encountered an error while lexing: %s", st->lexer->error);
+        return PIT_NIL;
+    case PIT_LEX_TOKEN_EOF:
+        if (eof != NULL) {
+            *eof = true;
+        } else {
+            pit_error(rt, "end-of-file while parsing");
+        }
+        return PIT_NIL;
+    case PIT_LEX_TOKEN_LPAREN: {
+        pit_value ret = PIT_NIL;
+        while (!match(st, PIT_LEX_TOKEN_RPAREN)) {
+            if (match(st, PIT_LEX_TOKEN_DOT)) {
+                ret = pit_parse(rt, st, eof);
+                if (match(st, PIT_LEX_TOKEN_RPAREN)) {
+                    break;
+                } else {
+                    pit_error(rt, "unterminated dotted list");
+                    return PIT_NIL;
+                }
+            } else {
+                ret = pit_value_cons(rt, pit_parse(rt, st, eof), ret);
+            }
+            if (rt->error != PIT_NIL || (eof != NULL && *eof)) {
+                pit_error(rt, "unterminated list");
+                return PIT_NIL; /* if we hit an error, stop!*/
+            }
+        }
+        ret = pit_value_list_reverse(rt, ret);
+        if (pit_value_sort(ret) == PIT_VALUE_SORT_REF) {
+            pit_annotation a = {0};
+            a.line = rt->source_line;
+            a.column = rt->source_column;
+            pit_annotation_set(rt, pit_value_as_ref(rt, ret), a);
+        }
+        return ret;
+    }
+    case PIT_LEX_TOKEN_LSQUARE: {
+        pit_value ret = PIT_NIL;
+        pit_value xs = PIT_NIL;
+        i64 len = 0;
+        while (!match(st, PIT_LEX_TOKEN_RSQUARE)) {
+            pit_value x = pit_parse(rt, st, eof);
+            xs = pit_value_cons(rt, x, xs);
+            len += 1;
+            if (rt->error != PIT_NIL || (eof != NULL && *eof)) {
+                pit_error(rt, "unterminated array literal");
+                return PIT_NIL;
+            }
+        }
+        ret = pit_value_array_new(rt, len);
+        while (xs != PIT_NIL) {
+            pit_value_array_set(rt, ret, --len, pit_value_cons_car(rt, xs));
+            xs = pit_value_cons_cdr(rt, xs);
+        }
+        return ret;
+    }
+    case PIT_LEX_TOKEN_QUOTE:
+        return pit_value_list(rt, 2, pit_symtab_intern_cstr(rt, "quote"), pit_parse(rt, st, eof));
+    case PIT_LEX_TOKEN_INTEGER_LITERAL: {
+        i64 idx = st->cur.start;
+        i64 base = 10;
+        i64 total = 0;
+        bool neg = false;
+        char c = st->lexer->input[idx++];
+        if (c == '-') {
+            neg = true;
+            if (idx < st->cur.end) {
+                c = st->lexer->input[idx++];
+            } else {
+                pit_error(rt, "malformed negative integer literal"); return PIT_NIL;
+            }
+        }
+        if (c == '0' && idx + 1 < st->cur.end) {
+            switch (st->lexer->input[idx++]) {
+            case 'b': base = 2; break;
+            case 'o': base = 8; break;
+            case 'x': base = 16; break;
+            default: pit_error(rt, "unknown integer base"); return PIT_NIL;
+            }
+        } else { total = digit_value(c); }
+        while (idx < st->cur.end) {
+            total *= base;
+            total += digit_value(st->lexer->input[idx++]);
+            if (total > 0x1ffffffffffff) {
+                pit_error(rt, "integer literal too large"); return PIT_NIL;
+            }
+        }
+        return pit_value_integer_new(rt, neg ? -total : total);
+    }
+    case PIT_LEX_TOKEN_STRING_LITERAL: {
+        char buf[256] = {0};
+        get_token_string(st, buf, sizeof(buf));
+        i64 len = (i64) pit_libc_string_strlen(buf);
+        i64 cur = 0;
+        for (i64 i = 1; i < len; ++i) {
+            if (buf[i] == '\\' && i + 1 < len) buf[cur++] = buf[++i];
+            else if (buf[i] != '"') buf[cur++] = buf[i];
+            else break;
+        }
+        return pit_value_bytes_new(rt, (u8 *) buf, cur);
+    }
+    case PIT_LEX_TOKEN_SYMBOL: {
+        char buf[256] = {0};
+        get_token_string(st, buf, sizeof(buf));
+        return pit_symtab_intern_cstr(rt, buf);
+    }
+    default:
+        pit_error(rt, "unexpected token: %s", pit_lex_token_name(t));
+        return PIT_NIL;
+    }
+}
diff --git a/pit/src/runtime.c b/pit/src/runtime.c
new file mode 100644
index 0000000..a8428c7
--- /dev/null
+++ b/pit/src/runtime.c
@@ -0,0 +1,116 @@
+#include <lcq/pit/utils.h>
+#include <lcq/pit/lexer.h>
+#include <lcq/pit/parser.h>
+#include <lcq/pit/runtime.h>
+#include <lcq/pit/library.h>
+
+enum pit_value_sort pit_value_sort(pit_value v) {
+    /* if this isn't a NaN, or it's a quiet NaN, this is a real double */
+    /* if (((v >> 52) & 0b011111111111) != 0b011111111111 || ((v >> 51) & 0b1) == 1) return PIT_VALUE_SORT_DOUBLE; */
+    if (((v >> 52) & 0x7ff) != 0x7ff || ((v >> 51) & 1) == 1) return PIT_VALUE_SORT_DOUBLE;
+    /* otherwise, we've packed something else in the significand
+         0 for signaling NaN -+
+           sign --+ +- 1 (NaN)| +- our sort tag       + our data
+                  | |         | |                     |
+                  s111111111110ttddddddddddddddddddddddddddddddddddddddddddddddddd */
+    /* return (v & 0b0000000000000110000000000000000000000000000000000000000000000000) >> 49; */
+    return (v & 0x6000000000000) >> 49; /* equivalent hex literal */
+}
+
+u64 pit_value_data(pit_value v) {
+    /* return  v & 0b0000000000000001111111111111111111111111111111111111111111111111; */
+    return v & 0x1ffffffffffff;
+}
+
+pit_runtime *pit_runtime_new(u8 *buf, i64 len) {
+    pit_arena *a = pit_arena_new(buf, len, sizeof(u8));
+    pit_runtime *ret = pit_arena_alloc_back(a, sizeof(*ret));
+    i64 heap_size = len / 4;
+    i64 annotations_size = len / 32;
+    i64 symtab_size = len / 16;
+    i64 stack_size = len / 32;
+    ret->heap = pit_arena_new(pit_arena_alloc_back(a, heap_size), heap_size, sizeof(pit_value_heavy));
+    ret->backbuffer = pit_arena_new(pit_arena_alloc_back(a, heap_size), heap_size, sizeof(pit_value_heavy));
+    ret->annotations = pit_vec_new(pit_annotated_ref)(pit_arena_alloc_back(a, annotations_size), annotations_size);
+    ret->backtrace = pit_vec_new(pit_annotated_ref)(pit_arena_alloc_back(a, annotations_size), annotations_size);
+    ret->symtab = pit_vec_new(pit_symtab_entry)(pit_arena_alloc_back(a, symtab_size), symtab_size);
+    ret->expr_stack = pit_vec_new(pit_value)(pit_arena_alloc_back(a, stack_size), stack_size);
+    ret->result_stack = pit_vec_new(pit_value)(pit_arena_alloc_back(a, stack_size), stack_size);
+    ret->program = pit_vec_new(pit_runtime_eval_ins)(pit_arena_alloc_back(a, stack_size), stack_size);
+    ret->saved_bindings = pit_vec_new(pit_value)(pit_arena_alloc_back(a, stack_size), stack_size);
+    ret->frozen_values = 0;
+    ret->frozen_symtab = 0;
+    ret->error = PIT_NIL;
+    ret->source_line = ret->source_column = -1;
+    ret->error_line = ret->error_column = -1;
+    pit_value nil = pit_symtab_intern_cstr(ret, "nil"); /* nil must be the 0th symbol for PIT_NIL to work */
+    pit_symtab_set(ret, nil, PIT_NIL);
+    pit_value truth = pit_symtab_intern_cstr(ret, "t");
+    pit_symtab_set(ret, truth, truth);
+    pit_runtime_freeze(ret);
+    return ret;
+}
+
+void pit_runtime_freeze(pit_runtime *rt) {
+    rt->frozen_values = rt->heap->next;
+    rt->frozen_symtab = rt->symtab->next;
+}
+void pit_runtime_reset(pit_runtime *rt) {
+    rt->heap->next = rt->frozen_values;
+    rt->symtab->next = rt->frozen_symtab;
+}
+
+pit_value pit_error_get(pit_runtime *rt) {
+    pit_value ret = rt->error;
+    rt->error = PIT_NIL;
+    return ret;
+}
+
+void pit_error(pit_runtime *rt, char *format, ...) {
+    if (rt->error == PIT_NIL) { /* only record the first error encountered */
+        char buf[1024] = {0};
+        va_list vargs;
+        va_start(vargs, format);
+        pit_libc_string_snprintf(buf, sizeof(buf), format, vargs);
+        va_end(vargs);
+        rt->error = PIT_T; /* we set the error now to prevent infinite recursion */
+        rt->error = pit_value_bytes_new_cstr(rt, buf); /* in case this errs also */
+        if (rt->error == PIT_NIL) rt->error = PIT_T;
+        rt->error_line = rt->source_line;
+        rt->error_column = rt->source_column;
+    }
+}
+
+void pit_annotation_set(struct pit_runtime *rt, pit_ref ref, pit_annotation annotation) {
+    pit_annotated_ref a;
+    a.ref = ref;
+    a.annotation = annotation;
+    if (pit_vec_push(pit_annotated_ref)(rt->annotations, a) < 0)
+        pit_error(rt, "annotation overflow");
+}
+pit_annotated_ref *pit_annotation_get(struct pit_runtime *rt, pit_ref ref) {
+    for (i64 i = 0; i < rt->annotations->next; ++i) {
+        pit_annotated_ref *a = pit_vec_get(pit_annotated_ref)(rt->annotations, i);
+        if (a == NULL) pit_error(rt, "failed to get annotation");
+        else if (a->ref == ref) {
+            return a;
+        }
+    }
+    return NULL;
+}
+
+void pit_runtime_eval_program_push_literal(pit_runtime *rt, pit_vec(pit_runtime_eval_ins) *s, pit_value x) {
+    pit_runtime_eval_ins ent;
+    ent.sort = PIT_RUNTIME_EVAL_INS_LITERAL;
+    ent.in.literal = x;
+    if (pit_vec_push(pit_runtime_eval_ins)(s, ent) < 0)
+        pit_error(rt, "evaluation program overflow");
+}
+void pit_runtime_eval_program_push_apply(pit_runtime *rt, pit_vec(pit_runtime_eval_ins) *s, i64 arity, pit_annotated_ref *annotation) {
+    pit_runtime_eval_ins ent;
+    ent.sort = PIT_RUNTIME_EVAL_INS_APPLY;
+    ent.in.apply.arity = arity;
+    ent.in.apply.annotation = annotation;
+    if (pit_vec_push(pit_runtime_eval_ins)(s, ent) < 0)
+        pit_error(rt, "evaluation program overflow");
+}
diff --git a/pit/src/runtime/dump.c b/pit/src/runtime/dump.c
new file mode 100644
index 0000000..3d5ec9c
--- /dev/null
+++ b/pit/src/runtime/dump.c
@@ -0,0 +1,100 @@
+#include <lcq/pit/runtime/dump.h>
+
+#define CHECK_BUF if (buf >= end) { return buf - start; }
+#define CHECK_BUF_LABEL(label) if (buf >= end) { goto label; }
+i64 pit_dump(pit_runtime *rt, char *buf, i64 len, pit_value v, bool readable) {
+    pit_value_heavy *h = NULL;
+    if (len <= 0) return 0;
+    switch (pit_value_sort(v)) {
+    case PIT_VALUE_SORT_DOUBLE:
+        #ifndef PIT_NO_DOUBLE
+        return pit_libc_string_snprintf(buf, (size_t) len, "%lf", pit_value_as_double(rt, v));
+        #else
+        return pit_string_snprintf(buf, (size_t) len, "<unsupported double>");
+        #endif
+    case PIT_VALUE_SORT_INTEGER:
+        return pit_libc_string_snprintf(buf, (size_t) len, "%ld", pit_value_as_integer(rt, v));
+    case PIT_VALUE_SORT_SYMBOL: {
+        pit_symtab_entry *ent = pit_symtab_lookup(rt, v);
+        if (ent
+            && pit_value_sort(ent->name) == PIT_VALUE_SORT_REF
+            && (h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ent->name)))
+        ) {
+            i64 i = 0;
+            for (; i < h->in.bytes.len && i < len - 1; ++i) {
+                buf[i] = (char) h->in.bytes.data[i];
+            }
+            return i;
+        } else {
+            return pit_libc_string_snprintf(buf, (size_t) len, "<broken symbol %ld>", pit_value_as_symbol(rt, v));
+        }
+    }
+    case PIT_VALUE_SORT_REF: {
+        pit_ref r = pit_value_as_ref(rt, v);
+        char *end = buf + len;
+        char *start = buf;
+        h = pit_value_ref_deref(rt, r);
+        if (!h) pit_libc_string_snprintf(buf, (size_t) len, "<ref %ld>", r);
+        else {
+            switch (h->hsort) {
+            case PIT_VALUE_HEAVY_SORT_CELL: {
+                CHECK_BUF; *(buf++) = '{';
+                CHECK_BUF; buf += pit_dump(rt, buf, end - buf, pit_value_cons_car(rt, h->in.cell), readable);
+                CHECK_BUF; *(buf++) = '}';
+                return buf - start;
+            }
+            case PIT_VALUE_HEAVY_SORT_CONS: {
+                pit_value cur = v;
+                CHECK_BUF_LABEL(list_end);
+                do {
+                    if (pit_value_is_cons(rt, cur)) {
+                        CHECK_BUF_LABEL(list_end); *(buf++) = ' ';
+                        CHECK_BUF_LABEL(list_end); buf += pit_dump(rt, buf, end - buf, pit_value_cons_car(rt, cur), readable);
+                    } else {
+                        CHECK_BUF_LABEL(list_end); buf += pit_libc_string_snprintf(buf, (size_t) (end - buf), " . ");
+                        CHECK_BUF_LABEL(list_end); buf += pit_dump(rt, buf, end - buf, cur, readable);
+                    }
+                } while (!pit_value_eq((cur = pit_value_cons_cdr(rt, cur)), PIT_NIL));
+                CHECK_BUF_LABEL(list_end); *(buf++) = ')';
+                list_end:
+                *start = '(';
+                return buf - start;
+            }
+            case PIT_VALUE_HEAVY_SORT_ARRAY: {
+                i64 i = 0;
+                CHECK_BUF_LABEL(array_end);
+                if (h->in.array.len == 0) {
+                    CHECK_BUF_LABEL(array_end); *(buf++) = '[';
+                } else for (; i < h->in.array.len; ++i) {
+                    CHECK_BUF_LABEL(array_end); *(buf++) = ' ';
+                    CHECK_BUF_LABEL(array_end); buf += pit_dump(rt, buf, end - buf, h->in.array.data[i], readable);
+                }
+                CHECK_BUF_LABEL(array_end); *(buf++) = ']';
+                array_end:
+                *start = '[';
+                return buf - start;
+            }
+            case PIT_VALUE_HEAVY_SORT_BYTES: {
+                i64 i = 0;
+                if (readable) { CHECK_BUF; buf[i++] = '"'; }
+                i64 maxlen = len - i;
+                for (i64 j = 0; i < maxlen && j < h->in.bytes.len;) {
+                    if (buf[i - 1] != '\\' && (h->in.bytes.data[j] == '\\' || h->in.bytes.data[j] == '"')) {
+                        CHECK_BUF; buf[i++] = '\\';
+                    }
+                    else {
+                        CHECK_BUF; buf[i++] = (char) h->in.bytes.data[j++];
+                    }
+                }
+                if (readable && i < len - 1) buf[i++] = '"';
+                return i;
+            }
+            default:
+                return pit_libc_string_snprintf(buf, (size_t) len, "<ref %ld>", r);
+            }
+        }
+        break;
+    }
+    }
+    return 0;
+}
diff --git a/pit/src/runtime/eval.c b/pit/src/runtime/eval.c
new file mode 100644
index 0000000..f5eba97
--- /dev/null
+++ b/pit/src/runtime/eval.c
@@ -0,0 +1,107 @@
+#include <lcq/pit/runtime/eval.h>
+
+pit_value pit_eval(pit_runtime *rt, pit_value top) {
+    i64 expr_stack_reset = rt->expr_stack->next;
+    i64 result_stack_reset = rt->result_stack->next;
+    i64 program_reset = rt->program->next;
+    // pit_vec_reset(pit_annotated_ref)(rt->backtrace);
+    if (pit_vec_push(pit_value)(rt->expr_stack, top) < 0)
+        pit_error(rt, "evaluation stack overflow");
+    /* first, convert the expression tree into "polish notation" in program */
+    while (rt->expr_stack->next > expr_stack_reset) {
+        pit_value cur = PIT_NIL;
+        if (rt->error != PIT_NIL) goto end;
+        if (pit_vec_pop(pit_value)(rt->expr_stack, &cur) < 0)
+            pit_error(rt, "evaluation stack underflow");
+        if (pit_value_is_cons(rt, cur)) { /* compound expressions: function/macro application special forms */
+            pit_value fsym = pit_value_cons_car(rt, cur);
+            bool is_symbol = pit_value_is_symbol(rt, fsym);
+            pit_annotated_ref *ann = pit_annotation_get(rt, pit_value_as_ref(rt, cur));
+            if (is_symbol && pit_symtab_is_symbol_special_form(rt, fsym)) { /* special forms */
+                pit_value f = pit_symtab_fget(rt, fsym);
+                pit_value args = pit_value_cons_cdr(rt, cur);
+                /* special forms are nativefuncs that directly manipulate the stacks
+                   basically macros, but we don't need to evaluate the return value */
+                pit_value_apply(rt, f, args);
+            } else if (is_symbol && pit_symtab_is_symbol_macro(rt, fsym)) { /* macros */
+                pit_value f = pit_symtab_fget(rt, fsym);
+                pit_value args = pit_value_cons_cdr(rt, cur);
+                pit_value res = pit_value_apply(rt, f, args);
+                if (pit_vec_push(pit_value)(rt->expr_stack, res) < 0)
+                    pit_error(rt, "evaluation stack overflow");
+            } else { /* normal functions */
+                pit_value args = pit_value_cons_cdr(rt, cur);
+                i64 argcount = 0;
+                while (args != PIT_NIL) {
+                    if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons_car(rt, args)) < 0)
+                        pit_error(rt, "evaluation stack overflow");
+                    args = pit_value_cons_cdr(rt, args);
+                    argcount += 1;
+                }
+                if (!is_symbol) {
+                    if (pit_vec_push(pit_value)(rt->expr_stack, fsym) < 0)
+                        pit_error(rt, "evaluation stack overflow");
+                }
+                pit_runtime_eval_program_push_apply(rt, rt->program, argcount, ann);
+                if (is_symbol) {
+                    pit_value f = pit_symtab_fget(rt, fsym);
+                    pit_runtime_eval_program_push_literal(rt, rt->program, f);
+                }
+            }
+        } else if (pit_value_is_symbol(rt, cur)) { /* unquoted symbols: variable lookup */
+            pit_symtab_entry *ent = pit_symtab_lookup(rt, cur);
+            if (ent->is_keyword) {
+                pit_runtime_eval_program_push_literal(rt, rt->program, cur);
+            } else {
+                pit_runtime_eval_program_push_literal(rt, rt->program, pit_symtab_get(rt, cur));
+            }
+        } else { /* other expressions evaluate to themselves! */
+            pit_runtime_eval_program_push_literal(rt, rt->program, cur);
+        }
+    }
+    /* then, execute the polish notation program from right to left
+       this has the nice consequence of putting the arguments in the right order */
+    for (i64 idx = rt->program->next - 1; idx >= program_reset; --idx) {
+        pit_runtime_eval_ins *ent = pit_vec_get(pit_runtime_eval_ins)(rt->program, idx);
+        if (ent == NULL) pit_error(rt, "evaluation program invalid");
+        if (rt->error != PIT_NIL) goto end;
+        switch (ent->sort) {
+        case PIT_RUNTIME_EVAL_INS_LITERAL:
+            if (pit_vec_push(pit_value)(rt->result_stack, ent->in.literal) < 0)
+                pit_error(rt, "evaluation result stack overflow");
+            break;
+        case PIT_RUNTIME_EVAL_INS_APPLY: {
+            pit_value f = PIT_NIL;
+            pit_value args = PIT_NIL;
+            if (pit_vec_pop(pit_value)(rt->result_stack, &f) < 0)
+                pit_error(rt, "evaluation result stack underflow");
+            for (i64 i = 0; i < ent->in.apply.arity; ++i) {
+                pit_value a = PIT_NIL;
+                if (pit_vec_pop(pit_value)(rt->result_stack, &a) < 0)
+                    pit_error(rt, "evaluation result stack underflow");
+                args = pit_value_cons(rt, a, args);
+            }
+            if (ent->in.apply.annotation != NULL) {
+                rt->source_line = ent->in.apply.annotation->annotation.line;
+                rt->source_column = ent->in.apply.annotation->annotation.column;
+                pit_vec_push(pit_annotated_ref)(rt->backtrace, *ent->in.apply.annotation);
+            }
+            if (pit_vec_push(pit_value)(rt->result_stack, pit_value_apply(rt, f, args)) < 0)
+                pit_error(rt, "evaluation result stack underflow");
+            break;
+        }
+        default:
+            pit_error(rt, "unknown program entry");
+            goto end;
+        }
+    }
+end: {
+        pit_value ret = PIT_NIL;
+        if (pit_vec_pop(pit_value)(rt->result_stack, &ret) < 0)
+            pit_error(rt, "evaluation result stack underflow");
+        rt->expr_stack->next = expr_stack_reset;
+        rt->result_stack->next = result_stack_reset;
+        rt->program->next = program_reset;
+        return ret;
+    }
+}
diff --git a/pit/src/runtime/gc.c b/pit/src/runtime/gc.c
new file mode 100644
index 0000000..fcb5f89
--- /dev/null
+++ b/pit/src/runtime/gc.c
@@ -0,0 +1,100 @@
+#include <lcq/pit/runtime/gc.h>
+
+static i64 gc_copy(pit_runtime *rt, pit_value_heavy *h) {
+    if (h->hsort == PIT_VALUE_HEAVY_SORT_FORWARDING_POINTER) {
+        return h->in.forwarding_pointer;
+    } else {
+        i64 ret = rt->backbuffer->next;
+        pit_value_heavy *g = pit_arena_alloc(rt->backbuffer);
+        *g = *h;
+        h->hsort = PIT_VALUE_HEAVY_SORT_FORWARDING_POINTER;
+        h->in.forwarding_pointer = ret;
+        return ret;
+    }
+}
+static pit_value gc_copy_value(pit_runtime *rt, pit_value v) {
+    if (pit_value_sort(v) == PIT_VALUE_SORT_REF) {
+        pit_ref r = pit_value_as_ref(rt, v);
+        pit_value_heavy *h = pit_value_ref_deref(rt, r);
+        i64 new = gc_copy(rt, h);
+        pit_annotated_ref *ann = pit_annotation_get(rt, r);
+        if (ann != NULL) {
+            pit_annotated_ref newann = *ann;
+            newann.ref = new;
+            if (pit_vec_push(pit_annotated_ref)(rt->backtrace, newann) < 0)
+                pit_error(rt, "annotation overflow");
+        }
+        return pit_value_ref_new(rt, new);
+    } else {
+        return v;
+    }
+}
+void pit_gc(pit_runtime *rt) {
+    rt->frozen_values = 0;
+    rt->frozen_symtab = 0;
+    pit_arena *fromspace = rt->heap;
+    pit_arena *tospace = rt->backbuffer;
+    pit_vec(pit_annotated_ref) *fromspace_ann = rt->annotations;
+    pit_vec(pit_annotated_ref) *tospace_ann = rt->backtrace;
+    pit_arena_reset(tospace);
+    pit_vec_reset(pit_annotated_ref)(tospace_ann);
+    /* populate tospace with immediately reachable values */
+    for (i64 i = 0; i < rt->symtab->next; ++i) {
+        pit_symtab_entry *ent = pit_vec_get(pit_symtab_entry)(rt->symtab, i);
+        if (ent == NULL) continue; /* TODO warn on failure here? */
+        ent->name = gc_copy_value(rt, ent->name);
+        ent->value = gc_copy_value(rt, ent->value);
+        ent->function = gc_copy_value(rt, ent->function);
+    }
+    for (i64 i = 0; i < rt->saved_bindings->next; ++i) {
+        pit_value *v = pit_vec_get(pit_value)(rt->saved_bindings, i);
+        if (v != NULL) *v = gc_copy_value(rt, *v); /* TODO warn on failure here? */
+    }
+    for (i64 scan = 0; scan < tospace->next; ++scan) {
+        pit_value_heavy *h = pit_arena_get(tospace, scan);
+        switch (h->hsort) {
+        case PIT_VALUE_HEAVY_SORT_CELL:
+            h->in.cell = gc_copy_value(rt, h->in.cell);
+            break;
+        case PIT_VALUE_HEAVY_SORT_CONS:
+            h->in.cons.car = gc_copy_value(rt, h->in.cons.car);
+            h->in.cons.cdr = gc_copy_value(rt, h->in.cons.cdr);
+            break;
+        case PIT_VALUE_HEAVY_SORT_ARRAY: {
+            i64 byte_len = 0; pit_mul(&byte_len, sizeof(pit_value), h->in.array.len);
+            pit_value *data = pit_arena_alloc_back(tospace, byte_len);
+            for (i64 i = 0; i < h->in.array.len; ++i) {
+                data[i] = gc_copy_value(rt, h->in.array.data[i]);
+            }
+            h->in.array.data = data;
+            break;
+        }
+        case PIT_VALUE_HEAVY_SORT_BYTES: {
+            u8 *data = pit_arena_alloc_back(tospace, h->in.bytes.len);
+            for (i64 i = 0; i < h->in.bytes.len; ++i) {
+                data[i] = h->in.bytes.data[i];
+            }
+            h->in.bytes.data = data;
+            break;
+        }
+        case PIT_VALUE_HEAVY_SORT_FUNC:
+            h->in.func.env = gc_copy_value(rt, h->in.func.env);
+            h->in.func.args = gc_copy_value(rt, h->in.func.args);
+            h->in.func.arg_rest_nm = gc_copy_value(rt, h->in.func.arg_rest_nm);
+            h->in.func.body = gc_copy_value(rt, h->in.func.body);
+            break;
+        case PIT_VALUE_HEAVY_SORT_NATIVEFUNC: break;
+        case PIT_VALUE_HEAVY_SORT_NATIVEDATA:
+            h->in.nativedata.tag = gc_copy_value(rt, h->in.nativedata.tag);
+            break;
+        case PIT_VALUE_HEAVY_SORT_FORWARDING_POINTER:
+            pit_error(rt, "garbage collection broken! encountered forwarding pointer in to-space");
+            break;
+        }
+    }
+    rt->heap = tospace;
+    rt->backbuffer = fromspace;
+    rt->annotations = tospace_ann;
+    rt->backtrace = fromspace_ann;
+    pit_vec_reset(pit_annotated_ref)(rt->backtrace);
+}
diff --git a/pit/src/runtime/macroexpand.c b/pit/src/runtime/macroexpand.c
new file mode 100644
index 0000000..13a4fdd
--- /dev/null
+++ b/pit/src/runtime/macroexpand.c
@@ -0,0 +1,111 @@
+#include <lcq/pit/runtime/macroexpand.h>
+
+pit_value pit_macroexpand(pit_runtime *rt, pit_value top) {
+    i64 expr_stack_reset = rt->expr_stack->next;
+    i64 result_stack_reset = rt->result_stack->next;
+    i64 program_reset = rt->program->next;
+    if (pit_vec_push(pit_value)(rt->expr_stack, top) < 0)
+        pit_error(rt, "macro expansion stack overflow");
+    while (rt->expr_stack->next > expr_stack_reset) {
+        pit_value cur;
+        if (rt->error != PIT_NIL) goto end;
+        if (pit_vec_pop(pit_value)(rt->expr_stack, &cur) < 0)
+            pit_error(rt, "macro expansion stack underflow");
+        if (pit_value_is_cons(rt, cur)) {
+            pit_value fsym = pit_value_cons_car(rt, cur);
+            bool is_symbol = pit_value_is_symbol(rt, fsym);
+            pit_annotated_ref *ann = pit_annotation_get(rt, pit_value_as_ref(rt, cur));
+            if (is_symbol && pit_symtab_is_symbol_macro(rt, fsym)) {
+                pit_value f = pit_symtab_fget(rt, fsym);
+                pit_value args = pit_value_cons_cdr(rt, cur);
+                pit_value res = pit_value_apply(rt, f, args);
+                if (pit_vec_push(pit_value)(rt->expr_stack, res) < 0)
+                    pit_error(rt, "macro expansion stack overflow");
+            } else if (is_symbol && pit_symtab_symbol_name_match_cstr(rt, fsym, "defer")) {
+                pit_value args = pit_value_cons_cdr(rt, cur);
+                pit_runtime_eval_program_push_literal(rt, rt->program, pit_value_cons_car(rt, args));
+            } else if (is_symbol && pit_symtab_symbol_name_match_cstr(rt, fsym, "quote")) {
+                pit_runtime_eval_program_push_literal(rt, rt->program, cur);
+            } else if (is_symbol && pit_symtab_symbol_name_match_cstr(rt, fsym, "lambda")) {
+                pit_value args = pit_value_cons_cdr(rt, cur);
+                pit_value bindings = pit_value_cons_car(rt, args);
+                pit_value body = pit_value_cons_cdr(rt, args);
+                i64 argcount = 0;
+                if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_list(rt, 2, pit_symtab_intern_cstr(rt, "defer"), bindings)) < 0)
+                    pit_error(rt, "macro expansion stack overflow");
+                while (body != PIT_NIL) {
+                    pit_value a = pit_value_cons_car(rt, body);
+                    if (pit_vec_push(pit_value)(rt->expr_stack, a) < 0)
+                        pit_error(rt, "macro expansion stack overflow");
+                    body = pit_value_cons_cdr(rt, body);
+                    argcount += 1;
+                }
+                pit_runtime_eval_program_push_apply(rt, rt->program, argcount + 1, ann);
+                pit_runtime_eval_program_push_literal(rt, rt->program, fsym);
+            } else {
+                pit_value args = pit_value_cons_cdr(rt, cur);
+                i64 argcount = 0;
+                while (args != PIT_NIL) {
+                    pit_value a = pit_value_cons_car(rt, args);
+                    if (pit_vec_push(pit_value)(rt->expr_stack, a) < 0)
+                        pit_error(rt, "macro expansion stack overflow");
+                    args = pit_value_cons_cdr(rt, args);
+                    argcount += 1;
+                }
+                if (!is_symbol) {
+                    if (pit_vec_push(pit_value)(rt->expr_stack, fsym) < 0)
+                        pit_error(rt, "macro expansion stack overflow");
+                }
+                pit_runtime_eval_program_push_apply(rt, rt->program, argcount, ann);
+                if (is_symbol) {
+                    pit_runtime_eval_program_push_literal(rt, rt->program, fsym);
+                }
+            }
+        } else {
+            pit_runtime_eval_program_push_literal(rt, rt->program, cur);
+        }
+    }
+    for (i64 idx = rt->program->next - 1; idx >= program_reset; --idx) {
+        pit_runtime_eval_ins *ent = pit_vec_get(pit_runtime_eval_ins)(rt->program, idx);
+        if (ent == NULL) pit_error(rt, "macro expansion program invalid");
+        if (rt->error != PIT_NIL) goto end;
+        switch (ent->sort) {
+        case PIT_RUNTIME_EVAL_INS_LITERAL:
+            if (pit_vec_push(pit_value)(rt->result_stack, ent->in.literal) < 0)
+                pit_error(rt, "macro expansion stack overflow");
+            break;
+        case PIT_RUNTIME_EVAL_INS_APPLY: {
+            pit_value f = PIT_NIL;
+            pit_value args = PIT_NIL;
+            pit_value app = PIT_NIL;
+            if (pit_vec_pop(pit_value)(rt->result_stack, &f) < 0)
+                pit_error(rt, "macro expansion stack underflow");
+            for (i64 i = 0; i < ent->in.apply.arity; ++i) {
+                pit_value a;
+                if (pit_vec_pop(pit_value)(rt->result_stack, &a) < 0)
+                    pit_error(rt, "macro expansion stack underflow");
+                args = pit_value_cons(rt, a, args);
+            }
+            app = pit_value_cons(rt, f, args);
+            if (ent->in.apply.annotation != NULL) {
+                pit_annotation_set(rt, pit_value_as_ref(rt, app), ent->in.apply.annotation->annotation);
+            }
+            if (pit_vec_push(pit_value)(rt->result_stack, app) < 0)
+                pit_error(rt, "macro expansion stack overflow");
+            break;
+        }
+        default:
+            pit_error(rt, "unknown program entry");
+            goto end;
+        }
+    }
+end: {
+        pit_value ret = PIT_NIL;
+        if (pit_vec_pop(pit_value)(rt->result_stack, &ret) < 0)
+            pit_error(rt, "macro expansion stack underflow");
+        rt->expr_stack->next = expr_stack_reset;
+        rt->result_stack->next = result_stack_reset;
+        rt->program->next = program_reset;
+        return ret;
+    }
+}
diff --git a/pit/src/runtime/symtab.c b/pit/src/runtime/symtab.c
new file mode 100644
index 0000000..d2bc51e
--- /dev/null
+++ b/pit/src/runtime/symtab.c
@@ -0,0 +1,118 @@
+#include <lcq/pit/runtime/symtab.h>
+
+pit_symtab_entry *pit_symtab_lookup(pit_runtime *rt, pit_value sym) {
+    pit_symbol s = pit_value_as_symbol(rt, sym);
+    return pit_vec_get(pit_symtab_entry)(rt->symtab, s);
+}
+pit_value pit_symtab_intern(pit_runtime *rt, u8 *nm, i64 len) {
+    if (rt->error != PIT_NIL) return PIT_NIL;
+    for (i64 sidx = 0; sidx < rt->symtab->next; ++sidx) {
+        pit_symtab_entry *sent = pit_vec_get(pit_symtab_entry)(rt->symtab, sidx);
+        if (sent == NULL) { pit_error(rt, "corrupted symbol table"); return PIT_NIL; }
+        if (pit_value_bytes_match(rt, sent->name, nm, len)) return pit_value_symbol_new(rt, sidx);
+    }
+    pit_symtab_entry ent;
+    ent.name = pit_value_bytes_new(rt, nm, len);
+    ent.value = PIT_NIL;
+    ent.function = PIT_NIL;
+    ent.is_macro = false;
+    ent.is_special_form = false;
+    ent.is_keyword = len >= 1 && nm[0] == ':';
+    i64 idx = pit_vec_push(pit_symtab_entry)(rt->symtab, ent);
+    if (idx < 0) { pit_error(rt, "failed to allocate symtab entry"); return PIT_NIL; }
+    return pit_value_symbol_new(rt, idx);
+}
+pit_value pit_symtab_intern_cstr(pit_runtime *rt, char *nm) {
+    return pit_symtab_intern(rt, (u8 *) nm, (i64) pit_libc_string_strlen(nm));
+}
+pit_value pit_symtab_symbol_name(pit_runtime *rt, pit_value sym) {
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return PIT_NIL; }
+    return ent->name;
+}
+bool pit_symtab_symbol_name_match(pit_runtime *rt, pit_value sym, u8 *buf, i64 len) {
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return PIT_NIL; }
+    return pit_value_bytes_match(rt, ent->name, buf, len);
+}
+bool pit_symtab_symbol_name_match_cstr(pit_runtime *rt, pit_value sym, char *s) {
+    return pit_symtab_symbol_name_match(rt, sym, (u8 *) s, (i64) pit_libc_string_strlen(s));
+}
+pit_value pit_symtab_get_value_cell(pit_runtime *rt, pit_value sym) {
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return PIT_NIL; }
+    return ent->value;
+}
+pit_value pit_symtab_get_function_cell(pit_runtime *rt, pit_value sym) {
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return PIT_NIL; }
+    return ent->function;
+}
+pit_value pit_symtab_get(pit_runtime *rt, pit_value sym) {
+    return pit_value_cell_get(rt, pit_symtab_get_value_cell(rt, sym), sym);
+}
+void pit_symtab_set(pit_runtime *rt, pit_value sym, pit_value v) {
+    pit_symbol idx = pit_value_as_symbol(rt, sym);
+    if (idx < rt->frozen_symtab) { pit_error(rt, "attempted to modify frozen symbol"); return; }
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return; }
+    if (pit_value_sort(ent->value) != PIT_VALUE_SORT_REF) {
+        ent->value = pit_value_cell_new(rt, PIT_NIL);
+    }
+    pit_value_cell_set(rt, ent->value, v, sym);
+}
+pit_value pit_symtab_fget(pit_runtime *rt, pit_value sym) {
+    return pit_value_cell_get(rt, pit_symtab_get_function_cell(rt, sym), sym);
+}
+void pit_symtab_fset(pit_runtime *rt, pit_value sym, pit_value v) {
+    pit_symbol idx = pit_value_as_symbol(rt, sym);
+    if (idx < rt->frozen_symtab) { pit_error(rt, "attempted to modify frozen symbol"); return; }
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return; }
+    if (pit_value_sort(ent->function) != PIT_VALUE_SORT_REF) {
+        ent->function = pit_value_cell_new(rt, PIT_NIL);
+    }
+    pit_value_cell_set(rt, ent->function, v, sym);
+}
+bool pit_symtab_is_symbol_macro(pit_runtime *rt, pit_value sym) {
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return false; }
+    return ent->is_macro;
+}
+void pit_symtab_symbol_mark_macro(pit_runtime *rt, pit_value sym) {
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return; }
+    ent->is_macro = true;
+}
+void pit_symtab_mset(pit_runtime *rt, pit_value sym, pit_value v) {
+    pit_symtab_fset(rt, sym, v);
+    pit_symtab_symbol_mark_macro(rt, sym);
+}
+bool pit_symtab_is_symbol_special_form(pit_runtime *rt, pit_value sym) {
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return false; }
+    return ent->is_special_form;
+}
+void pit_symtab_symbol_mark_special_form(pit_runtime *rt, pit_value sym) {
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return; }
+    ent->is_special_form = true;
+}
+void pit_symtab_sfset(pit_runtime *rt, pit_value sym, pit_value v) {
+    pit_symtab_fset(rt, sym, v);
+    pit_symtab_symbol_mark_special_form(rt, sym);
+}
+void pit_symtab_bind(pit_runtime *rt, pit_value sym, pit_value cell) {
+    /* although we cannot set frozen symbols, we can still bind them temporarily - no need to check */
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return; }
+    if (pit_vec_push(pit_value)(rt->saved_bindings, ent->value) < 0) pit_error(rt, "binding stack overflow");
+    ent->value = cell;
+}
+pit_value pit_symtab_unbind(pit_runtime *rt, pit_value sym) {
+    pit_symtab_entry *ent = pit_symtab_lookup(rt, sym);
+    if (!ent) { pit_error(rt, "bad symbol"); return PIT_NIL; }
+    pit_value old = ent->value;
+    if (pit_vec_pop(pit_value)(rt->saved_bindings, &ent->value) < 0) pit_error(rt, "binding stack underflow");
+    return old;
+}
diff --git a/pit/src/runtime/value.c b/pit/src/runtime/value.c
new file mode 100644
index 0000000..1e9d543
--- /dev/null
+++ b/pit/src/runtime/value.c
@@ -0,0 +1,76 @@
+#include <lcq/pit/runtime/value.h>
+
+pit_value pit_value_new(pit_runtime *rt, enum pit_value_sort s, u64 data) {
+    if (s == PIT_VALUE_SORT_DOUBLE) {
+        /* if (((data >> 52) & 0b011111111111) == 0b011111111111 && ((data >> 51) & 0b1) == 0) { */
+        if (((data >> 52) & 0x7ff) == 0x7ff && ((data >> 51) & 1) == 0) {
+            pit_error(rt, "attempted to create a signalling NaN double");
+            return PIT_NIL;
+        }
+        return data;
+    }
+    return
+        /* 0b1111111111110000000000000000000000000000000000000000000000000000 */
+        0xfff0000000000000
+        /* | (((u64) (s & 0b11)) << 49) */
+        | (((u64) (s & 3)) << 49)
+        /* | (data & 0b1111111111111111111111111111111111111111111111111); */
+        | (data & 0x1ffffffffffff);
+}
+
+bool pit_value_eq(pit_value a, pit_value b) {
+    return a == b;
+}
+
+bool pit_value_equal(pit_runtime *rt, pit_value a, pit_value b) {
+    if (pit_value_sort(a) != pit_value_sort(b)) return false;
+    switch (pit_value_sort(a)) {
+    case PIT_VALUE_SORT_DOUBLE:
+    case PIT_VALUE_SORT_INTEGER:
+    case PIT_VALUE_SORT_SYMBOL:
+        return pit_value_data(a) == pit_value_data(b);
+    case PIT_VALUE_SORT_REF: {
+        pit_value_heavy *ha = pit_value_ref_deref(rt, pit_value_as_ref(rt, a));
+        if (!ha) { pit_error(rt, "bad ref"); return false; }
+        pit_value_heavy *hb = pit_value_ref_deref(rt, pit_value_as_ref(rt, b));
+        if (!hb) { pit_error(rt, "bad ref"); return false; }
+        if (ha->hsort != hb->hsort) return false;
+        switch (ha->hsort) {
+        case PIT_VALUE_HEAVY_SORT_CELL:
+            return pit_value_equal(rt, ha->in.cell, hb->in.cell);
+        case PIT_VALUE_HEAVY_SORT_CONS:
+            return pit_value_equal(rt, ha->in.cons.car, hb->in.cons.car)
+                && pit_value_equal(rt, ha->in.cons.cdr, hb->in.cons.cdr);
+        case PIT_VALUE_HEAVY_SORT_ARRAY: {
+            if (ha->in.array.len != hb->in.array.len) return false;
+            for (i64 i = 0; i < ha->in.array.len; ++i) {
+                if (!pit_value_equal(rt, ha->in.array.data[i], hb->in.array.data[i])) return false;
+            }
+            return true;
+        }
+        case PIT_VALUE_HEAVY_SORT_BYTES: {
+            if (ha->in.bytes.len != hb->in.bytes.len) return false;
+            for (i64 i = 0; i < ha->in.bytes.len; ++i) {
+                if (ha->in.bytes.data[i] != hb->in.bytes.data[i]) return false;
+            }
+            return true;
+        }
+        case PIT_VALUE_HEAVY_SORT_FUNC:
+            return
+                pit_value_equal(rt, ha->in.func.env, hb->in.func.env)
+                && pit_value_equal(rt, ha->in.func.args, hb->in.func.args)
+                && pit_value_equal(rt, ha->in.func.body, hb->in.func.body);
+        case PIT_VALUE_HEAVY_SORT_NATIVEFUNC:
+            return ha->in.nativefunc.f == hb->in.nativefunc.f
+                && ha->in.nativefunc.data == hb->in.nativefunc.data;
+        case PIT_VALUE_HEAVY_SORT_NATIVEDATA:
+            return
+                pit_value_eq(ha->in.nativedata.tag, hb->in.nativedata.tag)
+                && ha->in.nativedata.data == hb->in.nativedata.data;
+        case PIT_VALUE_HEAVY_SORT_FORWARDING_POINTER:
+            return ha->in.forwarding_pointer == hb->in.forwarding_pointer;
+        }
+    }
+    }
+    return false;
+}
diff --git a/pit/src/runtime/value/array.c b/pit/src/runtime/value/array.c
new file mode 100644
index 0000000..1af84fd
--- /dev/null
+++ b/pit/src/runtime/value/array.c
@@ -0,0 +1,57 @@
+#include <lcq/pit/runtime/value/array.h>
+
+bool pit_value_is_array(pit_runtime *rt, pit_value a) {
+    return pit_value_is_ref_heavy_sort(rt, a, PIT_VALUE_HEAVY_SORT_ARRAY);
+}
+
+pit_value pit_value_array_new(pit_runtime *rt, i64 len) {
+    if (len < 0) { pit_error(rt, "failed to create array of negative size"); return PIT_NIL; }
+    i64 byte_len = 0; pit_mul(&byte_len, sizeof(pit_value), len);
+    pit_value *dest = pit_arena_alloc_array(rt->heap, byte_len);
+    if (!dest) { pit_error(rt, "failed to allocate array"); return PIT_NIL; }
+    for (i64 i = 0; i < len; ++i) dest[i] = PIT_NIL;
+    pit_value ret = pit_value_ref_heavy_new(rt);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to create new heavy value for array"); return PIT_NIL; }
+    h->hsort = PIT_VALUE_HEAVY_SORT_ARRAY;
+    h->in.array.data = dest;
+    h->in.array.len = len;
+    return ret;
+}
+pit_value pit_value_array_from_buf(pit_runtime *rt, pit_value *xs, i64 len) {
+    pit_value ret = pit_value_array_new(rt, len);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to deref heavy value for array"); return PIT_NIL; }
+    pit_libc_string_memcpy((u8 *) h->in.array.data, (u8 *) xs, (size_t) len * (size_t) sizeof(pit_value));
+    return ret;
+}
+i64 pit_value_array_len(pit_runtime *rt, pit_value arr) {
+    if (pit_value_sort(arr) != PIT_VALUE_SORT_REF) { pit_error(rt, "not a ref"); return -1; }
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, arr));
+    if (!h) { pit_error(rt, "bad ref"); return -1; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_ARRAY) { pit_error(rt, "not an array"); return -1; }
+    return h->in.array.len;
+}
+pit_value pit_value_array_get(pit_runtime *rt, pit_value arr, i64 idx) {
+    if (pit_value_sort(arr) != PIT_VALUE_SORT_REF) { pit_error(rt, "not a ref"); return PIT_NIL; }
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, arr));
+    if (!h) { pit_error(rt, "bad ref"); return PIT_NIL; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_ARRAY) { pit_error(rt, "not an array"); return PIT_NIL; }
+    if (idx < 0 || idx >= h->in.array.len) {
+        pit_error(rt, "array index out of bounds: %d", idx);
+        return PIT_NIL;
+    }
+    return h->in.array.data[idx];
+}
+pit_value pit_value_array_set(pit_runtime *rt, pit_value arr, i64 idx, pit_value v) {
+    if (pit_value_sort(arr) != PIT_VALUE_SORT_REF) { pit_error(rt, "not a ref"); return PIT_NIL; }
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, arr));
+    if (!h) { pit_error(rt, "bad ref"); return PIT_NIL; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_ARRAY) { pit_error(rt, "not an array"); return PIT_NIL; }
+    if (idx < 0 || idx >= h->in.array.len) {
+        pit_error(rt, "array index out of bounds: %d", idx);
+        return PIT_NIL;
+    }
+    h->in.array.data[idx] = v;
+    return v;
+}
diff --git a/pit/src/runtime/value/bytes.c b/pit/src/runtime/value/bytes.c
new file mode 100644
index 0000000..6a6edb6
--- /dev/null
+++ b/pit/src/runtime/value/bytes.c
@@ -0,0 +1,47 @@
+#include <lcq/pit/runtime/value/bytes.h>
+
+bool pit_value_is_bytes(pit_runtime *rt, pit_value a) {
+    return pit_value_is_ref_heavy_sort(rt, a, PIT_VALUE_HEAVY_SORT_BYTES);
+}
+pit_value pit_value_bytes_new(pit_runtime *rt, u8 *buf, i64 len) {
+    u8 *dest = pit_arena_alloc_back(rt->heap, len);
+    if (!dest) { pit_error(rt, "failed to allocate bytes"); return PIT_NIL; }
+    pit_libc_string_memcpy(dest, buf, (size_t) len);
+    pit_value ret = pit_value_ref_heavy_new(rt);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to create new heavy value for bytes"); return PIT_NIL; }
+    h->hsort = PIT_VALUE_HEAVY_SORT_BYTES;
+    h->in.bytes.data = dest;
+    h->in.bytes.len = len;
+    return ret;
+}
+pit_value pit_value_bytes_new_cstr(pit_runtime *rt, char *s) {
+    return pit_value_bytes_new(rt, (u8 *) s, (i64) pit_libc_string_strlen(s));
+}
+/* return true if v is a reference to bytes that are the same as those in buf */
+bool pit_value_bytes_match(pit_runtime *rt, pit_value v, u8 *buf, i64 len) {
+    if (pit_value_sort(v) != PIT_VALUE_SORT_REF) return false;
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, v));
+    if (!h) { pit_error(rt, "bad ref"); return false; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_BYTES) return false;
+    if (h->in.bytes.len != len) return false;
+    for (i64 i = 0; i < len; ++i)
+        if (h->in.bytes.data[i] != buf[i]) {
+            return false;
+        }
+    return true;
+}
+i64 pit_value_bytes_copy(pit_runtime *rt, pit_value v, u8 *buf, i64 maxlen) {
+    if (pit_value_sort(v) != PIT_VALUE_SORT_REF) { pit_error(rt, "not a ref"); return -1; }
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, v));
+    if (!h) { pit_error(rt, "bad ref"); return -1; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_BYTES) {
+        pit_error(rt, "invalid use of value as bytes");
+        return -1;
+    }
+    i64 len = maxlen < h->in.bytes.len ? maxlen : h->in.bytes.len;
+    for (i64 i = 0; i < len; ++i) {
+        buf[i] = h->in.bytes.data[i];
+    }
+    return len;
+}
diff --git a/pit/src/runtime/value/cell.c b/pit/src/runtime/value/cell.c
new file mode 100644
index 0000000..34b9226
--- /dev/null
+++ b/pit/src/runtime/value/cell.c
@@ -0,0 +1,47 @@
+#include <lcq/pit/runtime/value/cell.h>
+
+bool pit_value_is_cell(pit_runtime *rt, pit_value a) {
+    return pit_value_is_ref_heavy_sort(rt, a, PIT_VALUE_HEAVY_SORT_CELL);
+}
+pit_value pit_value_cell_new(pit_runtime *rt, pit_value v) {
+    pit_value ret = pit_value_ref_heavy_new(rt);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to create new heavy value for cell"); return PIT_NIL; }
+    h->hsort = PIT_VALUE_HEAVY_SORT_CELL;
+    h->in.cell = v;
+    return ret;
+}
+pit_value pit_value_cell_get(pit_runtime *rt, pit_value cell, pit_value sym) {
+    if (pit_value_sort(cell) != PIT_VALUE_SORT_REF) {
+        char buf[256];
+        i64 end = pit_dump(rt, buf, sizeof(buf) - 1, sym, false);
+        buf[end] = 0;
+        pit_error(rt, "attempted to get unbound variable/function: %s", buf);
+        return PIT_NIL;
+    }
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, cell));
+    if (!h) { pit_error(rt, "bad ref"); return PIT_NIL; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_CELL) {
+        pit_error(rt, "cell value ref does not point to cell");
+        return PIT_NIL;
+    }
+    return h->in.cell;
+}
+void pit_value_cell_set(pit_runtime *rt, pit_value cell, pit_value v, pit_value sym) {
+    if (pit_value_sort(cell) != PIT_VALUE_SORT_REF) {
+        char buf[256];
+        i64 end = pit_dump(rt, buf, sizeof(buf) - 1, sym, false);
+        buf[end] = 0;
+        pit_error(rt, "attempted to set unbound variable/function: %s", buf);
+        return;
+    }
+    pit_ref idx = pit_value_as_ref(rt, cell);
+    if (idx < rt->frozen_values) { pit_error(rt, "attempt to modify frozen cell"); return; }
+    pit_value_heavy *h = pit_value_ref_deref(rt, idx);
+    if (!h) { pit_error(rt, "bad ref"); return; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_CELL) {
+        pit_error(rt, "cell value ref does not point to cell");
+        return;
+    }
+    h->in.cell = v;
+}
diff --git a/pit/src/runtime/value/cons.c b/pit/src/runtime/value/cons.c
new file mode 100644
index 0000000..0f35631
--- /dev/null
+++ b/pit/src/runtime/value/cons.c
@@ -0,0 +1,110 @@
+#include <lcq/pit/runtime/value/cons.h>
+
+bool pit_value_is_cons(pit_runtime *rt, pit_value a) {
+    return pit_value_is_ref_heavy_sort(rt, a, PIT_VALUE_HEAVY_SORT_CONS);
+}
+pit_value pit_value_cons(pit_runtime *rt, pit_value car, pit_value cdr) {
+    pit_value ret = pit_value_ref_heavy_new(rt);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to create new heavy value for cons"); return PIT_NIL; }
+    h->hsort = PIT_VALUE_HEAVY_SORT_CONS;
+    h->in.cons.car = car;
+    h->in.cons.cdr = cdr;
+    return ret;
+}
+pit_value pit_value_cons_car(pit_runtime *rt, pit_value v) {
+    if (pit_value_sort(v) != PIT_VALUE_SORT_REF) return PIT_NIL;
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, v));
+    if (!h) { pit_error(rt, "bad ref"); return PIT_NIL; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_CONS) return PIT_NIL;
+    return h->in.cons.car;
+}
+pit_value pit_value_cons_cdr(pit_runtime *rt, pit_value v) {
+    if (pit_value_sort(v) != PIT_VALUE_SORT_REF) return PIT_NIL;
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, v));
+    if (!h) { pit_error(rt, "bad ref"); return PIT_NIL; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_CONS) return PIT_NIL;
+    return h->in.cons.cdr;
+}
+void pit_value_cons_setcar(pit_runtime *rt, pit_value v, pit_value x) {
+    if (pit_value_sort(v) != PIT_VALUE_SORT_REF) { pit_error(rt, "not a ref"); return; }
+    pit_ref idx = pit_value_as_ref(rt, v);
+    if (idx < rt->frozen_values) { pit_error(rt, "attempted to modify frozen cons"); return; }
+    pit_value_heavy *h = pit_value_ref_deref(rt, idx);
+    if (!h) { pit_error(rt, "bad ref"); return; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_CONS) { pit_error(rt, "not a cons"); return; }
+    h->in.cons.car = x;
+}
+void pit_value_cons_setcdr(pit_runtime *rt, pit_value v, pit_value x) {
+    if (pit_value_sort(v) != PIT_VALUE_SORT_REF) { pit_error(rt, "not a ref"); return; }
+    pit_ref idx = pit_value_as_ref(rt, v);
+    if (idx < rt->frozen_values) { pit_error(rt, "attempted to modify frozen cons"); return; }
+    pit_value_heavy *h = pit_value_ref_deref(rt, idx);
+    if (!h) { pit_error(rt, "bad ref"); return; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_CONS) { pit_error(rt, "not a cons"); return; }
+    h->in.cons.cdr = x;
+}
+
+pit_value pit_value_list(pit_runtime *rt, i64 num, ...) {
+    pit_value temp[64] = {0};
+    pit_value ret = PIT_NIL;
+    if (num > 64) { pit_error(rt, "failed to create list of size %d\n", num); return PIT_NIL; }
+    va_list elems;
+    va_start(elems, num);
+    for (i64 i = 0; i < num; ++i) {
+        temp[i] = va_arg(elems, pit_value);
+    }
+    va_end(elems);
+    for (i64 i = 0; i < num; ++i) {
+        ret = pit_value_cons(rt, temp[num - i - 1], ret);
+    }
+    return ret;
+}
+i64 pit_value_list_len(pit_runtime *rt, pit_value xs) {
+    i64 ret = 0;
+    while (xs != PIT_NIL) {
+        ret += 1;
+        xs = pit_value_cons_cdr(rt, xs);
+    }
+    return ret;
+}
+pit_value pit_value_list_append(pit_runtime *rt, pit_value xs, pit_value ys) {
+    pit_value ret = ys;
+    xs = pit_value_list_reverse(rt, xs);
+    while (xs != PIT_NIL) {
+        ret = pit_value_cons(rt, pit_value_cons_car(rt, xs), ret);
+        xs = pit_value_cons_cdr(rt, xs);
+    }
+    return ret;
+}
+pit_value pit_value_list_reverse(pit_runtime *rt, pit_value xs) {
+    pit_value ret = PIT_NIL;
+    while (xs != PIT_NIL) {
+        ret = pit_value_cons(rt, pit_value_cons_car(rt, xs), ret);
+        xs = pit_value_cons_cdr(rt, xs);
+    }
+    return ret;
+}
+pit_value pit_value_list_contains_eq(pit_runtime *rt, pit_value needle, pit_value haystack) {
+    while (haystack != PIT_NIL) {
+        if (pit_value_eq(needle, pit_value_cons_car(rt, haystack))) return PIT_T;
+        haystack = pit_value_cons_cdr(rt, haystack);
+    }
+    return PIT_NIL;
+}
+pit_value pit_value_list_contains_equal(pit_runtime *rt, pit_value needle, pit_value haystack) {
+    while (haystack != PIT_NIL) {
+        if (pit_value_equal(rt, needle, pit_value_cons_car(rt, haystack))) return PIT_T;
+        haystack = pit_value_cons_cdr(rt, haystack);
+    }
+    return PIT_NIL;
+}
+pit_value pit_value_list_plist_get(pit_runtime *rt, pit_value k, pit_value vs) {
+    while (vs != PIT_NIL) {
+        if (pit_value_eq(k, pit_value_cons_car(rt, vs))) {
+            return pit_value_cons_car(rt, pit_value_cons_cdr(rt, vs));
+        }
+        vs = pit_value_cons_cdr(rt, vs);
+    }
+    return PIT_NIL;
+}
diff --git a/pit/src/runtime/value/func.c b/pit/src/runtime/value/func.c
new file mode 100644
index 0000000..af039eb
--- /dev/null
+++ b/pit/src/runtime/value/func.c
@@ -0,0 +1,177 @@
+#include <lcq/pit/runtime/value/func.h>
+
+static pit_value free_vars(pit_runtime *rt, pit_value initial_bound, pit_value body) {
+    i64 expr_stack_reset = rt->expr_stack->next;
+    pit_value ret = PIT_NIL;
+    if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons(rt, initial_bound, body)) < 0) {
+        pit_error(rt, "free variable search stack overflow");
+        return PIT_NIL;
+    }
+    while (rt->expr_stack->next > expr_stack_reset) {
+        pit_value boundscur, bound, cur;
+        if (pit_vec_pop(pit_value)(rt->expr_stack, &boundscur) < 0) {
+            pit_error(rt, "free variable search stack underflow");
+            return PIT_NIL;
+        }
+        bound = pit_value_cons_car(rt, boundscur);
+        cur = pit_value_cons_cdr(rt, boundscur);
+        if (pit_value_is_cons(rt, cur)) {
+            pit_value fsym = pit_value_cons_car(rt, cur);
+            bool is_symbol = pit_value_is_symbol(rt, fsym);
+            pit_value fargs = pit_value_cons_cdr(rt, cur);
+            if (is_symbol && pit_symtab_symbol_name_match_cstr(rt, fsym, "lambda")) {
+                pit_value new_bound = pit_value_list_append(rt, pit_value_cons_car(rt, fargs), bound);
+                fargs = pit_value_cons_cdr(rt, fargs);
+                while (fargs != PIT_NIL) {
+                    if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons(rt, new_bound, pit_value_cons_car(rt, fargs))) < 0) {
+                        pit_error(rt, "free variable search stack overflow");
+                        return PIT_NIL;
+                    }
+                    fargs = pit_value_cons_cdr(rt, fargs);
+                }
+            } else if (is_symbol && pit_symtab_symbol_name_match_cstr(rt, fsym, "quote")) {
+                /* don't look inside quote!
+                   if we add other special forms, make sure to consider them here if necessary! */
+            } else {
+                while (fargs != PIT_NIL) {
+                    if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons(rt, bound, pit_value_cons_car(rt, fargs))) < 0) {
+                        pit_error(rt, "free variable search stack overflow");
+                        return PIT_NIL;
+                    }
+                    fargs = pit_value_cons_cdr(rt, fargs);
+                }
+                if (!is_symbol) {
+                    if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons(rt, bound, fsym)) < 0) {
+                        pit_error(rt, "free variable search stack overflow");
+                        return PIT_NIL;
+                    }
+                }
+            }
+        } else if (pit_value_is_symbol(rt, cur)) {
+            if (pit_value_list_contains_eq(rt, cur, bound) == PIT_NIL) {
+                ret = pit_value_cons(rt, cur, ret);
+            }
+        }
+    }
+    rt->expr_stack->next = expr_stack_reset;
+    return ret;
+}
+
+bool pit_value_is_func(pit_runtime *rt, pit_value a) {
+    return pit_value_is_ref_heavy_sort(rt, a, PIT_VALUE_HEAVY_SORT_FUNC);
+}
+bool pit_value_is_nativefunc(pit_runtime *rt, pit_value a) {
+    return pit_value_is_ref_heavy_sort(rt, a, PIT_VALUE_HEAVY_SORT_NATIVEFUNC);
+}
+pit_value pit_value_func_lambda(pit_runtime *rt, pit_value args, pit_value body) {
+    pit_value ret = pit_value_ref_heavy_new(rt);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to create new heavy value for lambda"); return PIT_NIL; }
+    pit_value expanded = pit_macroexpand(rt, pit_value_cons(rt, pit_symtab_intern_cstr(rt, "progn"), body));
+    pit_value freevars = free_vars(rt, args, expanded);
+    pit_value env = PIT_NIL;
+    while (freevars != PIT_NIL) {
+        pit_value sym = pit_value_cons_car(rt, freevars);
+        pit_value cell = pit_symtab_get_value_cell(rt, sym);
+        env = pit_value_cons(rt, pit_value_cons(rt, sym, cell), env);
+        freevars = pit_value_cons_cdr(rt, freevars);
+    }
+    h->hsort = PIT_VALUE_HEAVY_SORT_FUNC;
+    pit_value arg_cells = PIT_NIL;
+    pit_value arg_rest_nm = PIT_NIL;
+    pit_value separator = pit_symtab_intern_cstr(rt, "&");
+    while (args != PIT_NIL) {
+        pit_value nm = pit_value_cons_car(rt, args);
+        if (pit_value_eq(nm, separator)) {
+            pit_value next_nm = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+            if (next_nm == PIT_NIL) { pit_error(rt, "invalid & in lambda list"); return PIT_NIL; }
+            arg_rest_nm = next_nm;
+            arg_cells = pit_value_cons(rt, next_nm, arg_cells);
+            break;
+        } else {
+            arg_cells = pit_value_cons(rt, nm, arg_cells);
+            args = pit_value_cons_cdr(rt, args);
+        }
+    }
+    arg_cells = pit_value_list_reverse(rt, arg_cells);
+    h->in.func.args = arg_cells;
+    h->in.func.arg_rest_nm = arg_rest_nm;
+    h->in.func.env = env;
+    h->in.func.body = expanded;
+    return ret;
+}
+pit_value pit_value_nativefunc_new_with_data(pit_runtime *rt, pit_nativefunc f, void *data) {
+    pit_value ret = pit_value_ref_heavy_new(rt);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to create new heavy value for nativefunc"); return PIT_NIL; }
+    h->hsort = PIT_VALUE_HEAVY_SORT_NATIVEFUNC;
+    h->in.nativefunc.f = f;
+    h->in.nativefunc.data = data;
+    return ret;
+}
+pit_value pit_value_nativefunc_new(pit_runtime *rt, pit_nativefunc f) {
+    return pit_value_nativefunc_new_with_data(rt, f, NULL);
+}
+pit_value pit_value_apply(pit_runtime *rt, pit_value f, pit_value args) {
+    char buf[256] = {0};
+    if (pit_value_is_symbol(rt, f)) {
+        f = pit_symtab_fget(rt, f);
+    }
+    /* if f is not a symbol, assume it is a func or nativefunc
+       most commonly, this happens when you funcall a variable
+       with a function in the value cell, e.g. passing a lambda to a function */
+    switch (pit_value_sort(f)) {
+    case PIT_VALUE_SORT_REF: {
+        pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, f));
+        if (!h) { pit_error(rt, "bad ref"); return PIT_NIL; }
+        if (h->hsort == PIT_VALUE_HEAVY_SORT_FUNC) {
+            /* calling a Lisp function is simple! */
+            pit_value bound = PIT_NIL;
+            pit_value env = h->in.func.env;
+            while (env != PIT_NIL) { /* first, bind all entries in the closure */
+                pit_value b = pit_value_cons_car(rt, env);
+                pit_value nm = pit_value_cons_car(rt, b);
+                pit_symtab_bind(rt, nm, pit_value_cons_cdr(rt, b));
+                bound = pit_value_cons(rt, nm, bound);
+                env = pit_value_cons_cdr(rt, env);
+            }
+            pit_value anames = h->in.func.args;
+            while (anames != PIT_NIL) { /* bind all argument names to their values */
+                pit_value nm = pit_value_cons_car(rt, anames);
+                pit_value cell = pit_value_cell_new(rt, PIT_NIL);
+                if (h->in.func.arg_rest_nm != PIT_NIL && pit_value_eq(nm, h->in.func.arg_rest_nm)) {
+                    pit_value_cell_set(rt, cell, args, nm);
+                    pit_symtab_bind(rt, nm, cell);
+                    break;
+                } else {
+                    pit_value_cell_set(rt, cell, pit_value_cons_car(rt, args), nm);
+                    pit_symtab_bind(rt, nm, cell);
+                }
+                bound = pit_value_cons(rt, nm, bound);
+                args = pit_value_cons_cdr(rt, args);
+                anames = pit_value_cons_cdr(rt, anames);
+            }
+            pit_value ret = pit_eval(rt, h->in.func.body); /* evaluate the body */
+            while (bound != PIT_NIL) { /* unbind everything we bound earlier, in reverse */
+                pit_symtab_unbind(rt, pit_value_cons_car(rt, bound));
+                bound = pit_value_cons_cdr(rt, bound);
+            }
+            return ret;
+        } else if (h->hsort == PIT_VALUE_HEAVY_SORT_NATIVEFUNC) {
+            /* calling native functions is even simpler */
+            return h->in.nativefunc.f(rt, args, h->in.nativefunc.data);
+        } else {
+            i64 end = pit_dump(rt, buf, sizeof(buf) - 1, f, true);
+            buf[end] = 0;
+            pit_error(rt, "attempted to apply non-function ref: %s", buf);
+            return PIT_NIL;
+        }
+    }
+    default: {
+        i64 end = pit_dump(rt, buf, sizeof(buf) - 1, f, true);
+        buf[end] = 0;
+        pit_error(rt, "attempted to apply non-function value: %s", buf);
+        return PIT_NIL;
+    }
+    }
+}
diff --git a/pit/src/runtime/value/nativedata.c b/pit/src/runtime/value/nativedata.c
new file mode 100644
index 0000000..5c6fe2b
--- /dev/null
+++ b/pit/src/runtime/value/nativedata.c
@@ -0,0 +1,36 @@
+#include <lcq/pit/runtime/value/nativedata.h>
+
+bool pit_value_is_nativedata(pit_runtime *rt, pit_value a) {
+    return pit_value_is_ref_heavy_sort(rt, a, PIT_VALUE_HEAVY_SORT_NATIVEDATA);
+}
+pit_value pit_value_nativedata_new(pit_runtime *rt, pit_value tag, void *d) {
+    pit_value ret = pit_value_ref_heavy_new(rt);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to create new heavy value for nativedata"); return PIT_NIL; }
+    h->hsort = PIT_VALUE_HEAVY_SORT_NATIVEDATA;
+    h->in.nativedata.tag = tag;
+    h->in.nativedata.data = d;
+    return ret;
+}
+void *pit_value_nativedata_get(pit_runtime *rt, pit_value tag, pit_value v) {
+    pit_value_heavy *h = NULL;
+    if (pit_value_sort(v) != PIT_VALUE_SORT_REF) {
+        pit_error(rt, "value was not a reference");
+        return NULL;
+    }
+    h = pit_value_ref_deref(rt, pit_value_as_ref(rt, v));
+    if (!h) { pit_error(rt, "bad ref"); return NULL; }
+    if (h->hsort != PIT_VALUE_HEAVY_SORT_NATIVEDATA) {
+        pit_error(rt, "invalid use of value as nativedata");
+        return NULL;
+    }
+    if (!pit_value_eq(h->in.nativedata.tag, tag)) {
+        pit_error(rt, "native value does not match tag");
+        return NULL;
+    }
+    if (!h->in.nativedata.data) {
+        pit_error(rt, "nativedata was already freed");
+        return NULL;
+    }
+    return h->in.nativedata.data;
+}
diff --git a/pit/src/runtime/value/small.c b/pit/src/runtime/value/small.c
new file mode 100644
index 0000000..f07e405
--- /dev/null
+++ b/pit/src/runtime/value/small.c
@@ -0,0 +1,96 @@
+#include <lcq/pit/runtime/value/small.h>
+
+#ifndef PIT_NO_DOUBLE
+double pit_value_as_double(pit_runtime *rt, pit_value v) {
+    if (pit_value_sort(v) != PIT_VALUE_SORT_DOUBLE) {
+        pit_error(rt, "invalid use of value as double");
+        return 0.0;
+    }
+    union { double dval; u64 ival; } x;
+    x.ival = v;
+    return x.dval;
+}
+bool pit_value_is_double(pit_runtime *rt, pit_value a) {
+    (void) rt;
+    return pit_value_sort(a) == PIT_VALUE_SORT_DOUBLE;
+}
+pit_value pit_value_double_new(pit_runtime *rt, double d) {
+    union { double dval; u64 ival; } x;
+    x.dval = d;
+    return pit_value_new(rt, PIT_VALUE_SORT_DOUBLE, x.ival);
+}
+#endif
+
+i64 pit_value_as_integer(pit_runtime *rt, pit_value v) {
+    if (pit_value_sort(v) != PIT_VALUE_SORT_INTEGER) {
+        pit_error(rt, "invalid use of value as integer");
+        return -1;
+    }
+    u64 lo = pit_value_data(v);
+    return ((i64) (lo << 15)) >> 15; /* sign-extend low 49 bits */
+
+}
+bool pit_value_is_integer(pit_runtime *rt, pit_value a) {
+    (void) rt;
+    return pit_value_sort(a) == PIT_VALUE_SORT_INTEGER;
+}
+pit_value pit_value_integer_new(pit_runtime *rt, i64 i) {
+    return pit_value_new(rt, PIT_VALUE_SORT_INTEGER, 0x1ffffffffffff & (u64) i);
+}
+pit_value pit_value_bool_new(pit_runtime *rt, bool i) {
+    (void) rt;
+    return i ? PIT_T : PIT_NIL;
+}
+
+pit_symbol pit_value_as_symbol(pit_runtime *rt, pit_value v) {
+    if (pit_value_sort(v) != PIT_VALUE_SORT_SYMBOL) {
+        pit_error(rt, "invalid use of value as symbol");
+        return -1;
+    }
+    return (pit_symbol) (pit_value_data(v) & 0xffffffff);
+}
+bool pit_value_is_symbol(pit_runtime *rt, pit_value a) {
+    (void) rt;
+    return pit_value_sort(a) == PIT_VALUE_SORT_SYMBOL;
+}
+pit_value pit_value_symbol_new(pit_runtime *rt, pit_symbol s) {
+    return pit_value_new(rt, PIT_VALUE_SORT_SYMBOL, (u64) s);
+}
+
+pit_ref pit_value_as_ref(pit_runtime *rt, pit_value v) {
+    if (pit_value_sort(v) != PIT_VALUE_SORT_REF) {
+        pit_error(rt, "invalid use of value as ref");
+        return -1;
+    }
+    return (pit_ref) (pit_value_data(v) & 0xffffffff);
+}
+bool pit_value_is_ref(pit_runtime *rt, pit_value a) {
+    (void) rt;
+    return pit_value_sort(a) == PIT_VALUE_SORT_REF;
+}
+pit_value pit_value_ref_new(pit_runtime *rt, pit_ref r) {
+    return pit_value_new(rt, PIT_VALUE_SORT_REF, (u64) r);
+}
+pit_value pit_value_ref_heavy_new(pit_runtime *rt) {
+    pit_arena_index idx = pit_arena_alloc_index(rt->heap);
+    if (idx < 0) {
+        pit_error(rt, "failed to allocate space for heavy value");
+        return PIT_NIL;
+    }
+    return pit_value_ref_new(rt, idx);
+}
+pit_value_heavy *pit_value_ref_deref(pit_runtime *rt, pit_ref p) {
+    return pit_arena_get(rt->heap, p);
+}
+bool pit_value_is_ref_heavy_sort(pit_runtime *rt, pit_value a, enum pit_value_heavy_sort e) {
+    switch (pit_value_sort(a)) {
+    case PIT_VALUE_SORT_REF: {
+        pit_value_heavy *ha = pit_value_ref_deref(rt, pit_value_as_ref(rt, a));
+        if (!ha) { pit_error(rt, "bad ref"); return false; }
+        return ha->hsort == e;
+    }
+    default:
+        break;
+    }
+    return false;
+}
diff --git a/pit/src/utils.c b/pit/src/utils.c
new file mode 100644
index 0000000..75d59a6
--- /dev/null
+++ b/pit/src/utils.c
@@ -0,0 +1,101 @@
+#include <lcq/pit/utils.h>
+
+enum vsnprintf_mode {
+    VSNPRINTF_MODE_NORMAL,
+    VSNPRINTF_MODE_FLAGS,
+    VSNPRINTF_MODE_WIDTH,
+    VSNPRINTF_MODE_PRECISION,
+    VSNPRINTF_MODE_LENGTH_MOD,
+    VSNPRINTF_MODE_CONVERSION_SPEC
+};
+#define SCRATCH_LEN 256
+#define WRITE(c) { buf[idx++] = c; if (idx >= len - 1) goto done; }
+#define WRITE_SCRATCH(c) { scratch[sidx++] = c; if (sidx >= SCRATCH_LEN) goto error; }
+int pit_libc_string_vsnprintf(char *buf, size_t len, char *format, va_list ap) {
+    // vsnprintf
+    size_t idx = 0;
+    size_t flen = pit_libc_string_strlen(format);
+    size_t fidx = 0;
+    enum vsnprintf_mode mode = VSNPRINTF_MODE_NORMAL;
+    size_t sidx = 0;
+    char scratch[SCRATCH_LEN] = {0};
+    char length_mod = 0;
+    for (; fidx < flen && idx < len - 1; ++fidx) {
+        char c = format[fidx];
+        sidx = 0;
+        switch (mode) {
+        case VSNPRINTF_MODE_NORMAL:
+            if (c == '%') {
+                mode = VSNPRINTF_MODE_FLAGS;
+            } else WRITE(c);
+            break;
+        case VSNPRINTF_MODE_FLAGS:
+        case VSNPRINTF_MODE_WIDTH:
+        case VSNPRINTF_MODE_PRECISION:
+        case VSNPRINTF_MODE_LENGTH_MOD:
+            switch (c) {
+            case 'l': length_mod = 'l'; mode = VSNPRINTF_MODE_CONVERSION_SPEC; continue;
+            }
+            // fallthrough
+        case VSNPRINTF_MODE_CONVERSION_SPEC:
+            switch (c) {
+            case '%': WRITE('%'); mode = VSNPRINTF_MODE_NORMAL; break;
+            case 'd': {
+                long arg = 0;
+                if (length_mod == 'l') arg = va_arg(ap, long); else arg = va_arg(ap, int);
+                if (arg == 0) { WRITE('0') }
+                else {
+                    if (arg < 0) { WRITE('-'); arg = -arg; }
+                    while (arg != 0) { WRITE_SCRATCH('0' + (char) (arg % 10)); arg /= 10; }
+                    while (sidx > 0) { WRITE(scratch[sidx - 1]); sidx -= 1; }
+                }
+                mode = VSNPRINTF_MODE_NORMAL;
+                break;
+            }
+            case 'f': {
+                double arg = 0.0;
+                if (length_mod == 'l')
+                    arg = va_arg(ap, double);
+                else
+                    arg = va_arg(ap, double);
+                long wholepart = (long) arg;
+                double fracpart = arg - (double) wholepart;
+                if (wholepart == 0) { WRITE('0') }
+                else {
+                    while (wholepart != 0) { WRITE_SCRATCH('0' + (char) (wholepart % 10)); wholepart /= 10; }
+                    while (sidx > 0) { WRITE(scratch[sidx - 1]); sidx -= 1; }
+                }
+                WRITE('.');
+                for (int i = 0; i < 6; ++i) {
+                    fracpart *= 10.0;
+                    wholepart = (long) fracpart;
+                    fracpart -= (double) wholepart;
+                    WRITE('0' + (char) wholepart);
+                }
+                mode = VSNPRINTF_MODE_NORMAL;
+                break;
+            }
+            case 's': {
+                char *arg = va_arg(ap, char *);
+                while (*arg != 0) { WRITE(*arg); arg += 1; }
+                mode = VSNPRINTF_MODE_NORMAL;
+                break;
+            }
+            default: goto error;
+            }
+            break;
+        }
+    }
+done:
+    buf[idx] = 0;
+    return (int) idx;
+error:
+    return -1;
+}
+int pit_libc_string_snprintf(char *buf, size_t len, char *format, ...) {
+    va_list ap;
+    va_start(ap, format);
+    int ret = pit_libc_string_vsnprintf(buf, len, format, ap);
+    va_end(ap);
+    return ret;
+}