1 files changed, 92 insertions, 95 deletions

diff --git a/crates/elfmind/src/knowledge.rs b/crates/elfmind/src/knowledge.rs
index a610328..97ff118 100644
--- a/crates/elfmind/src/knowledge.rs
+++ b/crates/elfmind/src/knowledge.rs
@@ -1,86 +1,45 @@
-pub mod relation;
-pub use relation::*;
+pub mod traits; pub use traits::*;
+pub mod relation; pub use relation::*;
 
-use crate::time::*;
-use crate::item::*;
-use crate::character::*;
+pub use crate::noun::*;
 
 use std::collections::{HashMap, HashSet};
+use std::fmt::Display;
 use itertools::Itertools;
+use strum::IntoDiscriminant;
 
 use enum_map::EnumMap;
-use strum::IntoDiscriminant;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct Var { index: u64 }
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum Value {
-    Var(Var),
-    Item(Item),
-    Character(Character),
-    Time(Time),
-}
-impl From<Var> for Value { fn from(x: Var) -> Self {Value::Var(x)} }
-impl From<Item> for Value { fn from(x: Item) -> Self {Value::Item(x)} }
-impl From<Character> for Value { fn from(x: Character) -> Self {Value::Character(x)} }
-impl From<Time> for Value { fn from(x: Time) -> Self {Value::Time(x)} }
-impl TryFrom<Value> for Var {
-    type Error = ();
-    fn try_from(v: Value) -> Result<Self, Self::Error> {
-        if let Value::Var(x) = v { Ok(x) } else { Err(()) }
-    }
-}
-impl TryFrom<Value> for Item {
-    type Error = ();
-    fn try_from(v: Value) -> Result<Self, Self::Error> {
-        if let Value::Item(x) = v { Ok(x) } else { Err(()) }
-    }
-}
-impl TryFrom<Value> for Character {
-    type Error = ();
-    fn try_from(v: Value) -> Result<Self, Self::Error> {
-        if let Value::Character(x) = v { Ok(x) } else { Err(()) }
-    }
-}
-impl TryFrom<Value> for Time {
-    type Error = ();
-    fn try_from(v: Value) -> Result<Self, Self::Error> {
-        if let Value::Time(x) = v { Ok(x) } else { Err(()) }
+pub struct Var(pub u64);
+impl Display for Var {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "v{}", self.0)
     }
 }
 
 #[derive(Debug, Default)]
 pub struct Unification {
-    assignment: HashMap<Var, Value>,
+    assignment: HashMap<Var, Noun>,
 }
 impl Unification {
-    pub fn lookup(&self, v: &Var) -> Option<Value> {
+    pub fn lookup(&self, v: &Var) -> Option<Noun> {
         self.assignment.get(v).cloned()
     }
-    pub fn add(&mut self, v: Var, x: impl Into<Value>) -> bool {
+    pub fn add(&mut self, v: Var, x: impl Into<Noun>) -> bool {
         let y = x.into();
         if let Some(old) = self.assignment.get(&v) {
-            if let Value::Var(v2) = y {
-                self.add(v2, *old)
-            } else if let Value::Var(v2) = old {
-                self.add(*v2, y)
-            } else {
-                *old == y
-            }
+            *old == y
         } else {
             self.assignment.insert(v, y);
             true
         }
     }
-    pub fn unify_hole<A, B>(&mut self, h1: &Hole<A>, h2: &Hole<B>) -> bool
-    where Value: From<A>, Value: From<B>, A: Copy, B: Copy {
-        match (h1, h2) {
-            (Hole::Var(v1), Hole::Var(v2)) =>
-                self.add(*v1, *v2) && self.add(*v2, *v1),
-            (Hole::Val(x1), Hole::Val(x2)) => Value::from(*x1) == Value::from(*x2),
-            (Hole::Var(v1), Hole::Val(x2)) => self.add(*v1, *x2),
-            (Hole::Val(x1), Hole::Var(v2)) => self.add(*v2, *x1),
+    pub fn unify_hole<A, B>(&mut self, h1: &Hole<A>, x2: &B) -> bool
+    where Noun: From<A>, Noun: From<B>, A: Copy, B: Copy {
+        match h1 {
+            Hole::Val(x1) => Noun::from(*x1) == Noun::from(*x2),
+            Hole::Var(v1) => self.add(*v1, *x2),
         }
     }
 }
@@ -90,7 +49,20 @@ pub enum Hole<T> {
     Var(Var),
     Val(T),
 }
-impl<T: Clone + TryFrom<Value>> Hole<T> {
+impl<T: std::fmt::Debug> Display for Hole<T> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Var(v) => v.fmt(f),
+            Self::Val(x) => write!(f, "{:?}", x),
+        }
+    }
+}
+impl<A: std::fmt::Debug> DisplayNoun for Hole<A> {
+    fn display_noun(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self)
+    }
+}
+impl<T: Clone + TryFrom<Noun>> Hole<T> {
     pub fn substitute(&self, u: &Unification) -> Self {
         match self {
             x@Self::Var(v) => if let Some(y) = u.lookup(v) && let Ok(z) = T::try_from(y) {
@@ -105,8 +77,22 @@ impl<T: Clone + TryFrom<Value>> Hole<T> {
 
 #[derive(Debug, Clone)]
 pub struct Rule {
-    pub head: Relation,
-    pub body: Vec<Relation>,
+    pub head: RelationHole,
+    pub body: Vec<RelationHole>,
+}
+impl Display for Rule {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{} :- ", self.head)?;
+        #[allow(unstable_name_collisions)]
+        for mb in self.body.iter().map(Some).intersperse(None) {
+            if let Some(b) = mb {
+                write!(f, "{}", b)?;
+            } else {
+                write!(f, ", ")?;
+            }
+        }
+        std::fmt::Result::Ok(())
+    }
 }
 impl Rule {
     pub fn unify_body(&self, facts: &[&Relation]) -> Option<Unification> {
@@ -117,12 +103,40 @@ impl Rule {
         }
         Some(u)
     }
+    pub fn canonize(&mut self, mut next: u64) -> u64 {
+        let mut remap = HashMap::new();
+        let mut f = |v| {
+            if let Some(new) = remap.get(&v) {
+                *new
+            } else {
+                let new = Var(next);
+                next += 1;
+                remap.insert(v, new);
+                new
+            }
+        };
+        self.head = self.head.map_variables(&mut f);
+        for b in self.body.iter_mut() {
+            *b = b.map_variables(&mut f);
+        }
+        next
+    }
 }
 
 #[derive(Debug, Default, Clone)]
 pub struct Facts {
     facts: EnumMap<RelationDiscriminants, HashSet<Relation>>,
 }
+impl Display for Facts {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        for (_, s) in self.facts.iter() {
+            for r in s.iter() {
+                write!(f, "{}.\n", r)?;
+            }
+        }
+        std::fmt::Result::Ok(())
+    }
+}
 impl Facts {
     pub fn add(&mut self, f: Relation) -> bool {
         self.facts[f.discriminant()].insert(f)
@@ -148,6 +162,15 @@ pub struct Database {
     facts: Facts,
     rules: Vec<Rule>,
 }
+impl Display for Database {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.facts)?;
+        for r in self.rules.iter() {
+            write!(f, "{}.\n", r)?;
+        }
+        std::fmt::Result::Ok(())
+    }
+}
 impl Database {
     pub fn is_known(&self, r: &Relation) -> bool { self.facts.contains(r) }
     pub fn query<'a>(&'a mut self) -> Query<'a> {
@@ -176,16 +199,6 @@ impl<'a> Query<'a> {
     fn apply_rule(&self, r: &Rule, new_facts: &mut Facts, required_facts: QueryFactsToConsider) -> bool {
         // we don't need to consider every possible fact against each body term (naive evaluation)
         // instead, we can limit ourselves to the subset where at least one of the facts is new (semi-naive)
-        // let found: Vec<Unification> = r.body.iter()
-        //     .map(|r| {
-        //         let d = r.discriminant();
-        //         new_facts.with_sort(d).iter()
-        //             .chain(self.facts.with_sort(d).iter())
-        //             .chain(self.db.facts.with_sort(d).iter())
-        //     })
-        //     .multi_cartesian_product()
-        //     .filter_map(|fs| r.unify_body(&fs))
-        //     .collect();
         let mut found = Vec::new();
         // identify which slots of this rule body possibly have new facts to consider
         let changed_slots = r.body.iter()
@@ -216,8 +229,7 @@ impl<'a> Query<'a> {
                         QueryFactsToConsider::Query if i == cs =>
                              self.facts.with_sort(d).iter().chain(empty.iter()),
                         // otherwise, consider all facts - a new fact might be used alongside an unchanged fact!
-                        _ =>
-                            self.facts.with_sort(d).iter().chain(self.db.facts.with_sort(d).iter()),
+                        _ => self.facts.with_sort(d).iter().chain(self.db.facts.with_sort(d).iter()),
                     }
                 })
                 .multi_cartesian_product();
@@ -229,8 +241,10 @@ impl<'a> Query<'a> {
         }
         let mut changed = false;
         for u in found {
-            let new = r.head.substitute(&u);
-            if new.is_concrete() && !self.facts.contains(&new) && !self.db.facts.contains(&new) {
+            if let Some(new) = r.head.substitute(&u).concretize()
+                && !self.facts.contains(&new)
+                && !self.db.facts.contains(&new)
+            {
                 if new_facts.add(new) { changed = true; }
             }
         }
@@ -259,7 +273,8 @@ impl<'a> Query<'a> {
         }
         self
     }
-    pub fn rule(mut self, r: Rule) -> Self {
+    pub fn rule(mut self, mut r: Rule) -> Self {
+        r.canonize(0);
         self.rules.push(r);
         self
     }
@@ -286,21 +301,3 @@ impl<'a> Query<'a> {
         self.db.rules.extend_from_slice(&mut self.rules);
     }
 }
-
-#[derive(Debug, Default)]
-pub struct Context {
-    next_index: u64,
-    var_names: HashMap<Var, String>,
-}
-impl Context {
-    pub fn fresh(&mut self) -> Var {
-        let ret = Var { index: self.next_index };
-        self.next_index += 1;
-        ret
-    }
-    pub fn var(&mut self, nm: &str) -> Var {
-        let ret = self.fresh();
-        self.var_names.insert(ret, nm.to_owned());
-        ret
-    }
-}