keep working on vm

src/main.rs

@@ -59,12 +59,9 @@ pub fn main() {
         .unwrap();
     println!("{}", ast);
 
-    let mut ctx = Ctx {
-        local_names: vec!["foo"],
-        local_values: vec![Value::Keyword("foo")],
-    };
+    let mut ctx = vec![("foo", Value::Number(42.0))];
 
-    let result = eval(ast, &mut ctx).unwrap();
+    let result = eval(&ast, &mut ctx).unwrap();
 
     println!("{}", result);
 }

src/value.rs

@@ -19,18 +19,18 @@ pub struct Fn<'src> {
 }
 
 #[derive(Debug, PartialEq)]
-pub enum Value {
+pub enum Value<'src> {
     Nil,
     Boolean(bool),
     Number(f64),
-    Keyword(&'static str),
-    String(&'static str),
+    Keyword(&'src str),
+    String(&'src str),
     // on the heap for now
     Tuple(Rc<Vec<Self>>),
     // ref-counted, immutable, persistent
     List(Rc<Vector<Self>>),
     // ref-counted, immutable, persistent
-    Dict(Rc<HashMap<&'static str, Self>>),
+    Dict(Rc<HashMap<&'src str, Self>>),
     // Fn(Rc<Fn<'src>>),
     // Set(HashSet<Self>),
     // Sets are hard
@@ -44,8 +44,8 @@ pub enum Value {
     // pkgs, nses, tests
 }
 
-impl<'src> Clone for Value {
-    fn clone(&self) -> Value {
+impl<'src> Clone for Value<'src> {
+    fn clone(&self) -> Value<'src> {
         match self {
             Value::Nil => Value::Nil,
             Value::Boolean(b) => Value::Boolean(b.clone()),
@@ -59,7 +59,7 @@ impl<'src> Clone for Value {
     }
 }
 
-impl<'src> fmt::Display for Value {
+impl<'src> fmt::Display for Value<'src> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             Value::Nil => write!(f, "nil"),
@@ -89,7 +89,7 @@ impl<'src> fmt::Display for Value {
     }
 }
 
-impl Value {
+impl<'src> Value<'src> {
     pub fn bool(&self) -> bool {
         match self {
             Value::Nil | Value::Boolean(false) => false,

src/vm.rs

@@ -18,33 +18,31 @@ pub struct LudusError {
 // the branches for Ast::Block and Ast::If
 // to work with a mutable borrow of ctx
 pub struct Ctx<'src> {
-    locals: Vec<(&'src str, Value)>,
+    pub locals: Vec<(&'src str, Value<'src>)>,
 }
 
-impl Ctx {
-    pub fn resolve(&self, name: &str) -> Value {
-        let len = self.local_names.len();
-        let mut value = Value::Nil;
-        for i in (0..len).rev() {
-            if self.local_names[i] == name {
-                value = self.local_values[i].clone();
-                break;
-            }
+impl<'src> Ctx<'src> {
+    pub fn resolve(&self, name: &'src str) -> Value {
+        if let Some((_, val)) = self.locals.iter().rev().find(|(bound, _)| *bound == name) {
+            val.clone()
+        } else {
+            unreachable!()
         }
-        value
     }
 
-    pub fn store(&mut self, name: &'static str, value: Value) {
-        self.local_names.push(name);
-        self.local_values.push(value);
+    pub fn store(&mut self, name: &'src str, value: Value<'src>) {
+        self.locals.push((name, value));
     }
 }
 
-pub fn eval<'src>(ast: Ast<'src>, ctx: &mut Ctx) -> Result<Value, LudusError> {
+pub fn eval<'src, 'a>(
+    ast: &Ast<'src>,
+    ctx: &'a mut Vec<(&'src str, Value<'src>)>,
+) -> Result<Value<'src>, LudusError> {
     match ast {
         Ast::Nil => Ok(Value::Nil),
-        Ast::Boolean(b) => Ok(Value::Boolean(b)),
-        Ast::Number(n) => Ok(Value::Number(n)),
+        Ast::Boolean(b) => Ok(Value::Boolean(*b)),
+        Ast::Number(n) => Ok(Value::Number(*n)),
         Ast::Keyword(k) => Ok(Value::Keyword(k.clone())),
         Ast::String(s) => Ok(Value::String(s.clone())),
         Ast::Block(exprs) => {
@@ -55,30 +53,37 @@ pub fn eval<'src>(ast: Ast<'src>, ctx: &mut Ctx) -> Result<Value, LudusError> {
             Ok(result)
         }
         Ast::If(cond, if_true, if_false) => {
-            let truthy = eval((*cond).0, ctx)?.bool();
+            let truthy = eval(&cond.0, ctx)?.bool();
             if truthy {
                 let (if_true, _) = *if_true;
-                eval(if_true, ctx)
+                eval(&if_true, ctx)
             } else {
-                let (if_false, _) = *if_false;
-                eval(if_false, ctx)
+                let (if_false, _) = **if_false;
+                eval(&if_false, ctx)
             }
         }
         Ast::List(members) => {
             let mut vect = Vector::new();
             for member in members {
-                vect.push_back(eval(member.0, ctx)?)
+                vect.push_back(eval(&member.0, ctx)?)
             }
             Ok(Value::List(Rc::new(vect)))
         }
         Ast::Tuple(members) => {
             let mut vect = Vec::new();
             for member in members {
-                vect.push(eval(member.0, ctx)?);
+                vect.push(eval(&member.0, ctx)?);
             }
             Ok(Value::Tuple(Rc::new(vect)))
         }
-        Ast::Word(w) => Ok(ctx.resolve(w)),
+        Ast::Word(w) => {
+            let val = if let Some((_, value)) = ctx.iter().rev().find(|(name, _)| w == name) {
+                value.clone()
+            } else {
+                unreachable!()
+            };
+            Ok(val)
+        }
         _ => todo!(),
     }
 }