wip

src/ast/types.rs

@@ -27,6 +27,8 @@ pub enum Expr {
         expr: Box<Expr>,
         field: Label,
     },
+    Record(BTreeMap<Label, Expr>),
+    Vector(Vec<Expr>),
     /*
     Loop {
         body: Box<Expr>,
@@ -101,10 +103,10 @@ pub struct Label(pub String);
 pub struct EnvName(pub String);
 
 #[derive(PartialEq, PartialOrd, Debug, Clone)]
-pub struct Record(pub BTreeMap<Label, Expr>);
+pub struct Record(pub BTreeMap<Label, Value>);
 
 #[derive(PartialEq, PartialOrd, Debug, Clone)]
-pub struct Vector(pub Vec<Expr>);
+pub struct Vector(pub Vec<Value>);
 
 /// A Program.
 #[derive(PartialEq, PartialOrd, Debug)]

src/interpret/interpret.rs

@@ -2,7 +2,7 @@
 
 use super::types::*;
 
-use crate::ast;
+use crate::ast::{self, Record};
 
 pub fn run(
     program: ast::Program,
@@ -151,7 +151,6 @@ fn eval_expr(expr_env: &Env, state: &mut State, expr: &ast::Expr) -> Result<ast:
                     eval_expr(expr_env, state, &ast::UNIT)
                 }
 
-                /*
                 // access via labels
                 ast::Expr::Access { expr, field } => {
                     let rhs = eval_expr(expr_env, state, rhs)?;
@@ -162,7 +161,7 @@ fn eval_expr(expr_env: &Env, state: &mut State, expr: &ast::Expr) -> Result<ast:
                     } else {
                         todo!() // error nested field unreachable
                     }
-                } */
+                }
                 _ => todo!(),
             },
             _ => {
@@ -173,29 +172,34 @@ fn eval_expr(expr_env: &Env, state: &mut State, expr: &ast::Expr) -> Result<ast:
         },
     }
 }
-/*
-fn access_nested_field<'a>(
-    expr_env_name: &Env,
-    state: &'a mut State,
+fn access_nested_field(
+    expr_env: &Env,
+    state: &mut State,
     expr: &ast::Expr,
-    label: &ast::Label,
-) -> Result<&'a mut ast::Value, Error> {
-    //let lhs = eval_expr(expr_env, state, expr)?;
-    match expr {
-        ast::Expr::Var(var) => {
-            if let Some(mut value) = state.envs.get(&expr_env.name)?.get(&var)? {
-                match &value {
-                    &ast::Value::Record(record) => {
-                        record.
-                    }
-                    _ => todo!(),
+    labels: &[ast::Label],
+) -> Result<ast::Value, 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();
+            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()))?;
+                        } else {
+                            todo!()
                         }
                     }
+                    // vector, closure
+                    _ => todo!(), // unexpected
+                }
+            }
+            Ok(current)
         }
         _ => todo!(),
     }
 }
-*/
 
 fn defs_to_env(
     defs: Vec<ast::Definition>,

src/interpret/types.rs

@@ -3,6 +3,7 @@
 use crate::ast;
 use std::collections::BTreeMap;
 use std::collections::HashMap;
+use std::rc::Rc;
 
 #[derive(PartialEq, Debug, thiserror::Error)]
 pub enum Error {
@@ -58,7 +59,7 @@ pub struct State {
     pub variables: Variables,
 }
 
-pub struct Variables(pub HashMap<ast::Ref, ast::Value>);
+pub struct Variables(pub HashMap<ast::Ref, Rc<ast::Value>>);
 
 impl State {
     pub fn new(name: String) -> State {
@@ -78,9 +79,12 @@ impl State {
 
     pub fn insert_variable(&mut self, value: ast::Value) -> ast::Ref {
         let name = ast::Ref(self.variable_namer.next());
-        self.variables.0.insert(name.clone(), value);
+        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()
+    }
 }
 
 #[derive(PartialEq, Debug, Clone)]

src/parser/parser.rs

@@ -200,9 +200,7 @@ fn parse_record(tokens: &mut Tokens) -> ParseResult<ast::Expr> {
     if let Some(vect) = tokens.between(&Token::OpenCurly, &Token::CloseCurly, |tokens| {
         tokens.many_sep_by(&Token::Comma, parse_record_field_expr)
     })? {
-        Ok(Some(ast::Expr::Value(ast::Value::Record(ast::Record(
-            vect.into_iter().collect(),
-        )))))
+        Ok(Some(ast::Expr::Record(vect.into_iter().collect())))
     } else {
         Ok(None)
     }
@@ -212,9 +210,7 @@ fn parse_vector(tokens: &mut Tokens) -> ParseResult<ast::Expr> {
     if let Some(vect) = tokens.between(&Token::OpenBracket, &Token::CloseBracket, |tokens| {
         tokens.many_sep_by(&Token::Comma, parse_expr)
     })? {
-        Ok(Some(ast::Expr::Value(ast::Value::Vector(ast::Vector(
-            vect,
-        )))))
+        Ok(Some(ast::Expr::Vector(vect)))
     } else {
         Ok(None)
     }