wip

src/ast/types.rs

@@ -1,6 +1,7 @@
 //! Ast definition for Ayin.
 
 use std::collections::BTreeMap;
+use std::rc;
 
 /// An expression.
 #[derive(PartialEq, PartialOrd, Debug, Clone)]
@@ -103,10 +104,10 @@ pub struct Label(pub String);
 pub struct EnvName(pub String);
 
 #[derive(PartialEq, PartialOrd, Debug, Clone)]
-pub struct Record(pub BTreeMap<Label, Value>);
+pub struct Record(pub BTreeMap<Label, Ref>);
 
 #[derive(PartialEq, PartialOrd, Debug, Clone)]
-pub struct Vector(pub Vec<Value>);
+pub struct Vector(pub Vec<Ref>);
 
 /// A Program.
 #[derive(PartialEq, PartialOrd, Debug)]

src/interpret/interpret.rs

@@ -2,7 +2,7 @@
 
 use super::types::*;
 
-use crate::ast::{self, Record};
+use crate::ast;
 
 pub fn run(
     program: ast::Program,
@@ -153,6 +153,7 @@ fn eval_expr(expr_env: &Env, state: &mut State, expr: &ast::Expr) -> Result<ast:
 
                 // access via labels
                 ast::Expr::Access { expr, field } => {
+                    let lhs = eval_expr(expr_env, state, lhs)?;
                     let rhs = eval_expr(expr_env, state, rhs)?;
                     if let Some(mut nested_field) =
                         access_nested_field(expr_env, state, expr, field)?
@@ -174,19 +175,21 @@ fn eval_expr(expr_env: &Env, state: &mut State, expr: &ast::Expr) -> Result<ast:
 }
 fn access_nested_field(
     expr_env: &Env,
-    state: &mut State,
+    state: &State,
     expr: &ast::Expr,
     labels: &[ast::Label],
-) -> Result<ast::Value, Error> {
+) -> Result<ast::Ref, Error> {
     let lhs = eval_expr(&expr_env, state, expr)?;
     match lhs {
         ast::Value::Ref(reference) => {
-            let mut current: ast::Value = (*state.get_variable(&reference)).clone();
+            let mut current_ref = reference.clone();
+            let mut current: ast::Value = state.get_variable(&reference);
             for label in labels {
                 match current {
                     ast::Value::Record(record) => {
                         if let Some(next) = record.0.get(label) {
-                            current = eval_expr(&expr_env, state, &ast::Expr::Value(next.clone()))?;
+                            current_ref = next;
+                            current = state.get_variable(&current_ref);
                         } else {
                             todo!()
                         }
@@ -195,7 +198,7 @@ fn access_nested_field(
                     _ => todo!(), // unexpected
                 }
             }
-            Ok(current)
+            Ok(current_ref)
         }
         _ => todo!(),
     }

src/interpret/types.rs

@@ -59,7 +59,7 @@ pub struct State {
     pub variables: Variables,
 }
 
-pub struct Variables(pub HashMap<ast::Ref, Rc<ast::Value>>);
+pub struct Variables(pub HashMap<ast::Ref, ast::Value>);
 
 impl State {
     pub fn new(name: String) -> State {
@@ -82,8 +82,11 @@ impl State {
         self.variables.0.insert(name.clone(), Rc::new(value));
         name
     }
-    pub fn get_variable<'a>(&self, reference: &ast::Ref) -> Rc<ast::Value> {
-        self.variables.0.get(reference).unwrap().clone()
+    pub fn get_variable<'a>(&'a self, reference: &ast::Ref) -> &'a ast::Value {
+        self.variables.0.get(reference).unwrap()
+    }
+    pub fn set_variable(&mut self, reference: ast::Ref, new_value: ast::Value) {
+        self.variables.0.insert(reference, new_value)
     }
 }