Big refactorHEADmaster

13 files changed, 1182 insertions, 0 deletions

diff --git a/src/runtime/dump.c b/src/runtime/dump.c
new file mode 100644
index 0000000..3d5ec9c
--- /dev/null
+++ b/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/src/runtime/eval.c b/src/runtime/eval.c
new file mode 100644
index 0000000..f5eba97
--- /dev/null
+++ b/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/src/runtime/gc.c b/src/runtime/gc.c
new file mode 100644
index 0000000..fcb5f89
--- /dev/null
+++ b/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/src/runtime/macroexpand.c b/src/runtime/macroexpand.c
new file mode 100644
index 0000000..13a4fdd
--- /dev/null
+++ b/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/src/runtime/symtab.c b/src/runtime/symtab.c
new file mode 100644
index 0000000..d2bc51e
--- /dev/null
+++ b/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/src/runtime/value.c b/src/runtime/value.c
new file mode 100644
index 0000000..1e9d543
--- /dev/null
+++ b/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/src/runtime/value/array.c b/src/runtime/value/array.c
new file mode 100644
index 0000000..1af84fd
--- /dev/null
+++ b/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/src/runtime/value/bytes.c b/src/runtime/value/bytes.c
new file mode 100644
index 0000000..6a6edb6
--- /dev/null
+++ b/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/src/runtime/value/cell.c b/src/runtime/value/cell.c
new file mode 100644
index 0000000..34b9226
--- /dev/null
+++ b/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/src/runtime/value/cons.c b/src/runtime/value/cons.c
new file mode 100644
index 0000000..0f35631
--- /dev/null
+++ b/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/src/runtime/value/func.c b/src/runtime/value/func.c
new file mode 100644
index 0000000..af039eb
--- /dev/null
+++ b/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/src/runtime/value/nativedata.c b/src/runtime/value/nativedata.c
new file mode 100644
index 0000000..5c6fe2b
--- /dev/null
+++ b/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/src/runtime/value/small.c b/src/runtime/value/small.c
new file mode 100644
index 0000000..f07e405
--- /dev/null
+++ b/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;
+}