Cargo.toml

@@ -22,3 +22,8 @@ lalrpop = "0.19.6"
 [dev-dependencies]
 assert_cmd = "2.0.2"
 insta = { version = "1.9.0", features = ["glob"] }
+
+[profile.dev]
+# https://github.com/rust-lang/rust/issues/92163
+# https://github.com/rust-lang/rust/issues/92315
+incremental=false

README.md

@@ -0,0 +1,3 @@
+## Credits
+
+Many of the tests are adapted from [craftinginterpriters](https://github.com/munificent/craftinginterpreters/tree/master/test).

src/ast.rs

@@ -1,20 +1,25 @@
 use std::rc::Rc;
 
-#[derive(Debug, debug2::Debug, PartialEq)]
+#[derive(Debug /*/*, debug2::Debug*/*/, PartialEq)]
 
 crate enum Tree {
     Leaf(Literal),
     Define(String, Box<Tree>),
+    Set(String, Box<Tree>),
     If(Box<[Tree; 3]>),
-    Lambda(Lambda),
+    // Its easier to box the lambdas in the parser than the vm, as
+    // here we see all of them exactly once
+    Func(Rc<Func>),
     Branch(Vec<Tree>),
 }
 
-#[derive(Debug, debug2::Debug, PartialEq, Clone)]
+#[derive(Debug /*/*, debug2::Debug*/*/, PartialEq)]
+crate struct Func {
+    crate args: Vec<String>,
+    crate body: Vec<Tree>,
+}
 
-crate struct Lambda(crate Rc<[String]>, crate Rc<[Tree]>);
-
-#[derive(Debug, debug2::Debug, PartialEq)]
+#[derive(Debug /*/*, debug2::Debug*/*/, PartialEq)]
 
 crate enum Literal {
     Sym(String),

src/eval.rs

@@ -1,58 +1,82 @@
 use std::assert_matches::assert_matches;
+use std::cell::RefCell;
 use std::collections::HashMap;
+use std::rc::Rc;
 
 use crate::value::Value;
 use crate::{ast, prims};
 
-pub(crate) fn eval(t: &ast::Tree, env: &mut Env) -> Result<Value, RTError> {
+#[derive(/*debug2::Debug,*/ Debug, Clone)]
+crate struct Lambda {
+    crate func: Rc<ast::Func>,
+    crate captures: Rc<RefCell<Env>>,
+}
+
+pub(crate) fn eval(t: &ast::Tree, env: Rc<RefCell<Env>>) -> Result<Value, RTError> {
     Ok(match t {
         ast::Tree::Leaf(l) => match l {
-            ast::Literal::Sym(s) => match env.lookup(s) {
+            ast::Literal::Sym(s) => match env.borrow().lookup(s) {
                 Some(v) => v,
                 None => return err(format!("Undefined variable `{}`", s)),
             },
             ast::Literal::Num(v) => Value::Num(*v),
             ast::Literal::Bool(b) => Value::Bool(*b),
         },
-        ast::Tree::Lambda(l) => Value::Lambda(l.clone()),
+        ast::Tree::Func(l) => Value::Lambda(Lambda {
+            func: Rc::clone(l),
+            captures: Rc::clone(&env),
+        }),
         ast::Tree::Branch(args) => {
-            let Some(fun) = args.get(0) else { return err("No argument given".to_owned()) };
-            let fun = eval(fun, env)?;
-            let fun = fun.as_func()?;
+            let Some(fun) = args.get(0) else { return err("No func given".to_owned()) };
+
+            let fun = eval(fun, Rc::clone(&env))?.as_func()?;
+
             let args = args
                 .iter()
                 .skip(1)
-                .map(|a| eval(a, env))
+                .map(|a| eval(a, Rc::clone(&env)))
                 .collect::<Result<Vec<_>, _>>()?;
-            // return fun(&args);
+
             match fun {
                 Callable::Func(f) => f(&args)?,
                 Callable::Lambda(l) => {
-                    if l.0.len() == args.len() {
-                        let mut env = env.child();
-                        for (x, y) in l.0.iter().zip(args) {
+                    if l.func.args.len() == args.len() {
+                        // let mut env = env.child();
+                        let mut env = Env::child(Rc::clone(&l.captures));
+
+                        for (x, y) in l.func.args.iter().zip(args) {
                             env.define(x.clone(), y)
                         }
+                        let env = Rc::new(RefCell::new(env));
 
-                        let [main @ .., tail] = &l.1[..] else { unreachable!("Body has 1+ element by parser") };
+                        let [main @ .., tail] = &l.func.body[..] else { unreachable!("Body has 1+ element by parser") };
                         for i in main {
-                            eval(i, &mut env)?;
+                            eval(i, Rc::clone(&env))?;
                         }
 
-                        eval(tail, &mut env)?
+                        eval(tail, env)?
                     } else {
-                        return err(format!("Need {} args, got {}", l.0.len(), args.len()));
+                        return err(format!(
+                            "Need {} args, got {}",
+                            l.func.args.len(),
+                            args.len()
+                        ));
                     }
                 }
             }
         }
         ast::Tree::Define(name, to) => {
-            let val = eval(to, env)?;
-            env.define(name.to_owned(), val);
+            let val = eval(to, Rc::clone(&env))?;
+            env.borrow_mut().define(name.to_owned(), val);
+            Value::Trap
+        }
+        ast::Tree::Set(name, to) => {
+            let val = eval(to, Rc::clone(&env))?;
+            env.borrow_mut().set(name, val)?;
             Value::Trap
         }
         ast::Tree::If(box [cond, tcase, fcase]) => {
-            let b = eval(cond, env)?.as_bool()?;
+            let b = eval(cond, Rc::clone(&env))?.as_bool()?;
             let body = if b { tcase } else { fcase };
             eval(body, env)?
         }
@@ -66,40 +90,72 @@ pub(crate) fn err<T>(s: String) -> Result<T, RTError> {
     Err(RTError(s))
 }
 
-pub(crate) enum Callable<'a> {
-    Func(prims::Func),
-    Lambda(&'a ast::Lambda),
+pub(crate) enum Callable {
+    Func(prims::NativeFunc),
+    Lambda(Lambda),
 }
 
-pub(crate) struct Env<'a> {
-    pub(crate) vars: HashMap<String, Value>,
-    pub(crate) enclosing: Option<&'a Env<'a>>,
+#[derive(Clone /*, debug2::Debug*/)]
+pub(crate) struct Env {
+    vars: HashMap<String, Value>,
+    enclosing: Option<Rc<RefCell<Env>>>,
 }
 
-impl<'a> Env<'a> {
-    pub(crate) fn child(&'a self) -> Env<'a> {
+impl std::fmt::Debug for Env {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        struct Vars<'a>(&'a HashMap<String, Value>);
+
+        impl std::fmt::Debug for Vars<'_> {
+            fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+                f.debug_set().entries(self.0.keys()).finish()
+            }
+        }
+
+        f.debug_struct("Env")
+            .field("vars", &Vars(&self.vars))
+            .field("enclosing", &self.enclosing)
+            .finish()
+    }
+}
+
+impl Env {
+    pub(crate) fn child(this: Rc<RefCell<Self>>) -> Env {
         Env {
             vars: HashMap::new(),
-            enclosing: Some(self),
+            enclosing: Some(this),
         }
     }
 
     pub(crate) fn lookup(&self, s: &str) -> Option<Value> {
         if let Some(v) = self.vars.get(s) {
             Some(v.clone())
-        } else if let Some(parent) = self.enclosing {
-            parent.lookup(s)
+        } else if let Some(parent) = &self.enclosing {
+            parent.borrow().lookup(s)
         } else {
             None
         }
     }
 
     pub(crate) fn define(&mut self, name: String, val: Value) {
+        assert_ne!(val, Value::Trap); // TODO: Better error
+
+        // TODO: Error on previous def
         self.vars.insert(name, val);
     }
+
+    crate fn set(&mut self, name: &str, val: Value) -> Result<(), RTError> {
+        if let Some(loc) = self.vars.get_mut(name) {
+            *loc = val;
+            Ok(())
+        } else if let Some(parent) = &self.enclosing {
+            parent.borrow_mut().set(name, val)
+        } else {
+            err(format!("Tried to `set!` un `define`d var `{}`", name))
+        }
+    }
 }
 
-pub(crate) fn default_env() -> Env<'static> {
+pub(crate) fn default_env() -> Env {
     let mut vars = HashMap::new();
 
     for (name, fun) in prims::prims() {

src/grammar.lalrpop

@@ -17,9 +17,11 @@ Trees = Tree+;
 pub(crate) Tree: Tree = {
     "(" <Tree+> ")" => Tree::Branch(<>),
     "(" "define" <Sym> <BTree> ")" => Tree::Define(<>),
-    "(" "define" "(" <name:Sym> <args:RcSlice<Sym>> ")" <body:RcSlice<Tree>> ")" => Tree::Define(name, Box::new(Tree::Lambda(Lambda(args, body)))),
+    "(" "define" "(" <name:Sym> <args:Sym*> ")" <body:Trees> ")" 
+        => Tree::Define(name, Box::new(Tree::Func(Rc::new(Func{args, body})))),
     "(" "if" <Tree> <Tree> <Tree> ")" => Tree::If(Box::new([<>])),
-    "(" "lambda (" <RcSlice<Sym>> ")" <RcSlice<Tree>> ")" => Tree::Lambda(Lambda(<>)),
+    "(" "lambda (" <args:Sym*> ")" <body:Trees> ")" => Tree::Func(Rc::new(Func{<>})),
+    "(" "set!" <Sym> <BTree> ")" => Tree::Set(<>),
     Literal => Tree::Leaf(<>),
 }
 

src/main.rs

@@ -4,7 +4,9 @@
 #![feature(crate_visibility_modifier)]
 #![feature(let_else)]
 
+use std::cell::RefCell;
 use std::io;
+use std::rc::Rc;
 
 use rustyline::validate::{
     MatchingBracketValidator, ValidationContext, ValidationResult, Validator,
@@ -33,9 +35,9 @@ fn main() {
 fn run_file(file: &str) -> io::Result<()> {
     let src = std::fs::read_to_string(file)?;
     let tree = grammar::FileParser::new().parse(&src).unwrap();
-    let mut env = eval::default_env();
+    let env = Rc::new(RefCell::new(eval::default_env()));
     for i in tree {
-        eval::eval(&i, &mut env).unwrap();
+        eval::eval(&i, Rc::clone(&env)).unwrap();
     }
     Ok(())
 }
@@ -46,14 +48,23 @@ fn repl() {
         brackets: MatchingBracketValidator::new(),
     }));
 
-    let mut env = eval::default_env();
+    let env = Rc::new(RefCell::new(eval::default_env()));
 
     while let Ok(line) = rl.readline("> ") {
         rl.add_history_entry(&line);
 
         let tree = grammar::TreeParser::new().parse(&line).unwrap();
         // dbg!(&tree);
-        println!("< {:?}", eval::eval(&tree, &mut env))
+        match eval::eval(&tree, Rc::clone(&env)) {
+            Ok(v) => {
+                // Cant use == because it will panic. This is the only
+                // valid comparison to trap
+                if !matches!(v, value::Value::Trap) {
+                    println!("{}", v)
+                }
+            }
+            Err(e) => println!("! {}", e.0),
+        }
     }
 }
 

src/prims.rs

@@ -1,9 +1,12 @@
 use crate::eval::{err, RTError};
 use crate::value::Value;
 
-crate type Func = fn(&[Value]) -> Result<Value, RTError>;
 
-crate fn prims() -> &'static [(&'static str, Func)] {
+type Result = std::result::Result<Value, RTError>;
+
+crate type NativeFunc = for<'a> fn(&'a [Value]) -> Result;
+
+crate fn prims() -> &'static [(&'static str, NativeFunc)] {
     &[
         ("*", mul),
         ("+", add),
@@ -21,25 +24,27 @@ crate fn prims() -> &'static [(&'static str, Func)] {
         (">", gt),
         ("<=", le),
         (">=", ge),
+
+        ("_Z_debug", z_debug)
     ]
 }
 
 // TODO: DRY +-/*
-fn add(args: &[Value]) -> Result<Value, RTError> {
+fn add(args: &[Value]) -> Result {
     args.iter()
         .map(Value::as_num)
         .try_fold(0.0, |a, b| Ok(a + b?))
         .map(Value::Num)
 }
 
-fn mul(args: &[Value]) -> Result<Value, RTError> {
+fn mul(args: &[Value]) -> Result {
     args.iter()
         .map(Value::as_num)
         .try_fold(1.0, |a, b| Ok(a * b?))
         .map(Value::Num)
 }
 
-fn div(args: &[Value]) -> Result<Value, RTError> {
+fn div(args: &[Value]) -> Result {
     let init = args
         .get(0)
         .ok_or_else(|| RTError("`div` needs at least one argument".to_owned()))?
@@ -53,7 +58,7 @@ fn div(args: &[Value]) -> Result<Value, RTError> {
     }))
 }
 
-fn sub(args: &[Value]) -> Result<Value, RTError> {
+fn sub(args: &[Value]) -> Result {
     let init = args
         .get(0)
         .ok_or_else(|| RTError("`sub` needs at least one argument".to_owned()))?
@@ -67,17 +72,17 @@ fn sub(args: &[Value]) -> Result<Value, RTError> {
     }))
 }
 
-fn equals(args: &[Value]) -> Result<Value, RTError> {
+fn equals(args: &[Value]) -> Result {
     Ok(Value::Bool(args.array_windows().all(|[l, r]| l == r)))
 }
 
-fn display(args: &[Value]) -> Result<Value, RTError> {
+fn display(args: &[Value]) -> Result {
     let [arg] = args else {return err("To many args to `display`".to_owned())};
-    print!("{:?}", arg);
+    print!("{}", arg);
     Ok(Value::Trap)
 }
 
-fn newline(args: &[Value]) -> Result<Value, RTError> {
+fn newline(args: &[Value]) -> Result {
     if !args.is_empty() {
         return err("Newline takes no args".to_owned());
     }
@@ -85,7 +90,7 @@ fn newline(args: &[Value]) -> Result<Value, RTError> {
     Ok(Value::Trap)
 }
 
-fn abs(args: &[Value]) -> Result<Value, RTError> {
+fn abs(args: &[Value]) -> Result {
     let [v] = args else { return err("abs takes 1 arg".to_owned()) };
     let ans = v.as_num()?.abs();
     Ok(Value::Num(ans))
@@ -95,7 +100,7 @@ crate fn compare_core(
     args: &[Value],
     f: fn(f64, f64) -> bool,
     name: &'static str,
-) -> Result<Value, RTError> {
+) -> Result {
     for [l, r] in args.array_windows() {
         let (Value::Num(l), Value::Num(r)) = (l,r) else 
         { 
@@ -114,7 +119,7 @@ crate fn compare_core(
 macro_rules! cmps {
     ($(($name:ident $op:tt))*) => {
         $(
-            fn $name(args: &[Value]) -> Result<Value, RTError> {
+            fn $name(args: &[Value]) -> Result {
                 compare_core(args, |l, r| l $op r, stringify!($op))
             }
         )*
@@ -122,3 +127,8 @@ macro_rules! cmps {
 }
 
 cmps! { (lt <) (gt >) (le <=) (ge >=) }
+
+fn z_debug(args: &[Value]) -> Result {
+    eprintln!("{:?}", args);
+    Ok(Value::Trap)
+}

src/snapshots/handball__tests__run-pass@4-1-6-Assignments.scm.snap

@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass r7rs-spec\\4-1-6-Assignments.scm"
+
+---
+3.05.0

src/snapshots/handball__tests__run-pass@ambig-scope.scm.snap

@@ -0,0 +1,13 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: run-pass ambig-scope.scm
+
+---
+
+42.0
+1.0
+2.0
+3.0
+2.0
+1.0

src/snapshots/handball__tests__run-pass@assign-closures.scm.snap

@@ -0,0 +1,11 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\assign-closures.scm"
+
+---
+1.0
+2.0
+2.0
+3.0
+

src/snapshots/handball__tests__run-pass@assign-shadowed-later.scm.snap

@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\assign-shadowed-later.scm"
+
+---
+1.0
+0.0
+

src/snapshots/handball__tests__run-pass@bagel-donut.scm.snap

@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\bagel-donut.scm"
+
+---
+4.0
+2.0
+

src/snapshots/handball__tests__run-pass@capture.scm.snap

@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: run-pass capture.scm
+
+---
+#<procedure>
+2.0
+

src/snapshots/handball__tests__run-pass@close-over-function-param.scm.snap

@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\close-over-function-param.scm"
+
+---
+77.0

src/snapshots/handball__tests__run-pass@close-over-later-variable.scm.snap

@@ -0,0 +1,8 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\close-over-later-variable.scm"
+
+---
+2.0
+1.0

src/snapshots/handball__tests__run-pass@close-unused.scm.snap

@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\close-unused.scm"
+
+---
+7.0

src/snapshots/handball__tests__run-pass@closed-closure-in-function.scm.snap

@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\closed-closure-in-function.scm"
+
+---
+1.0

src/snapshots/handball__tests__run-pass@curry.scm.snap

@@ -0,0 +1,8 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: run-pass curry.scm
+
+---
+3.0
+

src/snapshots/handball__tests__run-pass@gnarly-i.scm.snap

@@ -0,0 +1,10 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\gnarly-i.scm"
+
+---
+3.0
+2.0
+1.0
+

src/snapshots/handball__tests__run-pass@mutate-levels.scm.snap

@@ -0,0 +1,13 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\mutate-levels.scm"
+
+---
+2.0
+3.0
+3.0
+3.0
+7.0
+8.0
+

src/snapshots/handball__tests__run-pass@nested-assign.scm.snap

@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\nested-assign.scm"
+
+---
+1.0

src/snapshots/handball__tests__run-pass@nested-closure.scm.snap

@@ -0,0 +1,10 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\nested-closure.scm"
+
+---
+1.0
+2.0
+3.0
+

src/snapshots/handball__tests__run-pass@objects-are-a-poor-mans-closure.scm.snap

@@ -0,0 +1,20 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\objects-are-a-poor-mans-closure.scm"
+
+---
+1.0
+7.0
+1.0
+7.0
+
+8.0
+2.0
+8.0
+2.0
+
+9.0
+9.0
+
+

src/snapshots/handball__tests__run-pass@open-closure-in-function.scm.snap

@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\open-closure-in-function.scm"
+
+---
+1.0

src/snapshots/handball__tests__run-pass@reference-closure-multiple-times.scm.snap

@@ -0,0 +1,8 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\reference-closure-multiple-times.scm"
+
+---
+1.0
+1.0

src/snapshots/handball__tests__run-pass@reuse-closure-slot.scm.snap

@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\reuse-closure-slot.scm"
+
+---
+1.0

src/snapshots/handball__tests__run-pass@scope.scm.snap

@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\scope.scm"
+
+---
+7.0
+2.0
+

src/snapshots/handball__tests__run-pass@shadow-closure-with-local.scm.snap

@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\shadow-closure-with-local.scm"
+
+---
+0.0
+1.0
+

src/snapshots/handball__tests__run-pass@unused-later-closures.scm.snap

@@ -0,0 +1,8 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\unused-later-closures.scm"
+
+---
+1.0
+1.0

src/snapshots/handball__tests__run-pass@use-after-close.scm.snap

@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\use-after-close.scm"
+
+---
+1.0

src/snapshots/handball__tests__run-pass@val-or-var.scm.snap

@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\val-or-var.scm"
+
+---
+0.0
+1.0
+

src/test/run-pass/ambig-scope.scm

@@ -0,0 +1,22 @@
+#lang scheme
+
+(define (displayln x)
+  (newline)
+  (display x))
+
+(define (ambig1 x)
+  (lambda (x) x))
+
+(displayln ((ambig1 13) 42))
+
+(define (ambig2 a)
+  (displayln a)
+  (define a- a)
+  (lambda (b)
+    (displayln b)
+    (lambda (a)
+      (displayln a)
+      (displayln b)
+      (displayln a-))))
+
+(((ambig2 1) 2) 3)

src/test/run-pass/capture.scm

@@ -0,0 +1,13 @@
+#lang scheme
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (const x)
+  (lambda () x))
+
+(define two-thunk (const 2))
+
+(displayln two-thunk)
+(displayln (two-thunk))

src/test/run-pass/closure/assign-closures.scm

@@ -0,0 +1,28 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/assign_to_closure.lox
+
+(define f #f)
+(define g #f)
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+((lambda ()
+   (define local 1)
+
+   (define (f_)
+     (displayln local)
+     (set! local 2)
+     (displayln local))
+
+   (set! f f_)
+
+   (define (g_)
+     (displayln local)
+     (set! local 3)
+     (displayln local))
+
+   (set! g g_)))
+
+(f)
+(g)

src/test/run-pass/closure/assign-shadowed-later.scm

@@ -0,0 +1,17 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/assign_to_shadowed_later.lox
+
+(define a 0)
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+((lambda ()
+   (define (assign)
+     (set! a 1))
+
+   (define a 2)
+   (assign)
+   (displayln a)))
+
+(displayln a)

src/test/run-pass/closure/bagel-donut.scm

@@ -0,0 +1,14 @@
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (make-print x)
+  (define (print)
+    (displayln x))
+  print)
+
+(define print-2 (make-print 2))
+(define print-4 (make-print 4))
+
+(print-4)
+(print-2)

src/test/run-pass/closure/close-over-function-param.scm

@@ -0,0 +1,10 @@
+(define f #f)
+
+(define (foo param)
+  (define (f_)
+    (display param))
+  (set! f f_))
+
+(foo 77)
+
+(f)

src/test/run-pass/closure/close-over-later-variable.scm

@@ -0,0 +1,14 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/close_over_later_variable.lox
+
+(define (f)
+  (define a 1)
+  (define b 2)
+
+  (define (g)
+    (display b)
+    (newline)
+    (display a))
+
+  (g))
+
+(f)

src/test/run-pass/closure/close-unused.scm

@@ -0,0 +1,6 @@
+((lambda ()
+   (define a 1)
+
+   (if #f (lambda () a) 0)))
+
+(display 7)

src/test/run-pass/closure/closed-closure-in-function.scm

@@ -0,0 +1,11 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/closed_closure_in_function.lox
+
+(define f #f)
+
+((lambda ()
+   (define local 1)
+   (define (f_)
+     (display local))
+   (set! f f_)))
+
+(f)

src/test/run-pass/closure/gnarly-i.scm

@@ -0,0 +1,22 @@
+#lang scheme
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (outer)
+  (define x 1)
+
+  (define (middle)
+    (define (inner)
+      (displayln x))
+    (displayln 2)
+    inner)
+
+  (displayln 3)
+
+  middle)
+
+(define mid (outer))
+(define in (mid))
+(in)

src/test/run-pass/closure/mutate-levels.scm

@@ -0,0 +1,24 @@
+(define x 2)
+
+(define (show-x)
+  (display x)
+  (newline))
+
+(show-x)
+(set! x 3)
+(show-x)
+
+((lambda ()
+   (define x 7)
+   (show-x)
+   (set! x 8)
+   (show-x)))
+
+((lambda ()
+   (define (show-x)
+     (display x)
+     (newline))
+   (define x 7)
+   (show-x)
+   (set! x 8)
+   (show-x)))

src/test/run-pass/closure/nested-assign.scm

@@ -0,0 +1,8 @@
+(define (outer)
+  (define x 0)
+  (define (y)
+    (set! x 1))
+  (y)
+  (display x))
+
+(outer)

src/test/run-pass/closure/nested-closure.scm

@@ -0,0 +1,26 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/nested_closure.lox
+#lang scheme
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define f #f)
+
+(define (f1)
+  (define a 1)
+  (define (f2)
+    (define b 2)
+    (define (f3)
+      (define c 3)
+      (define (f4)
+        (displayln a)
+        (displayln b)
+        (displayln c))
+      (set! f f4))
+    (f3))
+  (f2))
+
+(f1)
+
+(f)

src/test/run-pass/closure/objects-are-a-poor-mans-closure.scm

@@ -0,0 +1,43 @@
+#lang scheme
+
+(define get-x 1)
+(define get-y 2)
+(define do-print 3)
+(define add 4)
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (vector x y)
+  (define (add-to other)
+    (vector (+ x (other get-x)) (+ y (other get-y))))
+
+  (lambda (message)
+    (if (= message get-x)
+        x
+        (if (= message get-y)
+            y
+            (if (= message add)
+                add-to
+                (if (= message do-print)
+                    ((lambda ()
+                       (displayln x)
+                       (displayln y)
+                       (newline)))
+                    ((lambda ()
+                       (displayln -99)
+                       0))))))))
+
+(define v-1-7 (vector 1 7))
+(displayln (v-1-7 get-x))
+(displayln (v-1-7 get-y))
+(v-1-7 do-print)
+
+(define v-8-2 (vector 8 2))
+(displayln (v-8-2 get-x))
+(displayln (v-8-2 get-y))
+(v-8-2 do-print)
+
+(define v-9-9 ((v-8-2 add) v-1-7))
+(v-9-9 do-print)

src/test/run-pass/closure/open-closure-in-function.scm

@@ -0,0 +1,9 @@
+#lang scheme
+
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/open_closure_in_function.lox
+
+((lambda ()
+   (define local 1)
+   (define (f)
+     (display local))
+   (f)))

src/test/run-pass/closure/reference-closure-multiple-times.scm

@@ -0,0 +1,14 @@
+#lang scheme
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/reference_closure_multiple_times.lox
+
+(define f #f)
+
+((lambda ()
+   (define a 1)
+   (define (f_)
+     (display a)
+     (newline)
+     (display a))
+   (set! f f_)))
+
+(f)

src/test/run-pass/closure/reuse-closure-slot.scm

@@ -0,0 +1,15 @@
+#lang scheme
+
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/reuse_closure_slot.lox
+
+((lambda ()
+   (define f #f)
+   ((lambda ()
+      (define a 1)
+      (define (f_)
+        (display a))
+      (set! f f_)))
+
+   ((lambda ()
+      (define b 2)
+      (f)))))

src/test/run-pass/closure/scope.scm

@@ -0,0 +1,13 @@
+(define x 2)
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (gy y)
+  x)
+(define (gx x)
+  x)
+
+(displayln (gx 7))
+(displayln (gy 7))

src/test/run-pass/closure/shadow-closure-with-local.scm

@@ -0,0 +1,15 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/shadow_closure_with_local.lox
+; TODO: Forbid this https://discordapp.com/channels/571040468092321801/618895179343986688/925533402592079912
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+((lambda ()
+   (define foo 0)
+   (define (f)
+     ((lambda ()
+        (displayln foo)
+        (define foo 1)
+        (displayln foo))))
+   (f)))

src/test/run-pass/closure/unused-later-closures.scm

@@ -0,0 +1,19 @@
+(define closure #f)
+
+((lambda ()
+   (define a 1)
+
+   ((lambda ()
+      (define b 2)
+
+      (define (get-a)
+        a)
+
+      (set! closure get-a)
+
+      (if #f (lambda () b) 0)))
+
+   (display (closure))))
+
+(newline)
+(display (closure))

src/test/run-pass/closure/use-after-close.scm

@@ -0,0 +1,8 @@
+(define (outer)
+  (define x 1)
+  (define (inner)
+    (display x))
+  inner)
+
+(define clousre (outer))
+(clousre)

src/test/run-pass/closure/val-or-var.scm

@@ -0,0 +1,19 @@
+(define globalSet #f)
+(define globalGet #f)
+
+(define (main)
+  (define a 0)
+
+  (define (set)
+    (set! a 1))
+  (define (get)
+    (display a)
+    (newline))
+
+  (set! globalSet set)
+  (set! globalGet get))
+
+(main)
+(globalGet)
+(globalSet)
+(globalGet)

src/test/run-pass/curry.scm

@@ -0,0 +1,10 @@
+#lang scheme
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (curry2 f)
+  (lambda (l) (lambda (r) (f l r))))
+
+(displayln (((curry2 +) 1) 2))

src/test/run-pass/fib.scm

@@ -1,21 +1,28 @@
 #lang scheme
 
-(define (displayln x) (display x) (newline))
+(define (displayln x)
+  (display x)
+  (newline))
 
-(define (my-or a b) (if a #t b)) ; Test was written before we had `or`
+(define (my-or a b)
+  (if a #t b)) ; Test was written before we had `or`
 
-
-(define (fib-base? n) (my-or (= n 1) (= n 0)))
+(define (fib-base? n)
+  (my-or (= n 1) (= n 0)))
 
 (define (fib n)
-  (if (fib-base? n) 1
-      (+ (fib (- n 1)) (fib (- n 2)))))
+  (if (fib-base? n) 1 (+ (fib (- n 1)) (fib (- n 2)))))
 
-
-(define (pfib n) (displayln n) (displayln (fib n)) (newline))
+(define (pfib n)
+  (displayln n)
+  (displayln (fib n))
+  (newline))
 
 (define (pfibs n)
-  (if (= n (- 1)) 0 ; Hack
-      ((lambda () (pfib n) (pfibs (- n 1)))))) ; Hack
+  (if (= n (- 1))
+      0 ; Hack
+      ((lambda ()
+         (pfib n)
+         (pfibs (- n 1)))))) ; Hack
 
 (pfibs 10)

src/test/run-pass/funcs.scm

@@ -1,6 +1,8 @@
 #lang scheme
 
-(define (displayln x) (display x) (newline))
+(define (displayln x)
+  (display x)
+  (newline))
 
 (define add1 +)
 (displayln (add1 2 3))
@@ -8,5 +10,6 @@
 (define add2 (lambda (a b) (+ a b)))
 (displayln (add2 5 6))
 
-(define (add3 a b) (+ a b))
+(define (add3 a b)
+  (+ a b))
 (displayln (add3 5 9))

src/test/run-pass/lambda-calc.scm

@@ -1,18 +1,24 @@
 #lang scheme
 
-(define (displayln x) (display x) (newline))
-(define (printbool x) (displayln (bool->int x)))
+(define (displayln x)
+  (display x)
+  (newline))
+(define (printbool x)
+  (displayln (bool->int x)))
 
-(define (true x y) x)
-(define (false x y) y)
-(define (and x y) (x y x))
-(define (or x y) (x x y))
-(define (not x) (x false true))
+(define (true x y)
+  x)
+(define (false x y)
+  y)
+(define (and x y)
+  (x y x))
+(define (or x y)
+  (x x y))
+(define (not x)
+  (x false true))
 
 (define (bool->int x)
-  (if 
-   (equal? x true) 1 
-   (if (equal? x false) 0 (- 1))))
+  (if (equal? x true) 1 (if (equal? x false) 0 (- 1))))
 
 (printbool true)
 (printbool false)

src/test/run-pass/multi.scm

@@ -1,5 +1,8 @@
 #lang scheme
 
-(define (multi) 1 2 3)
+(define (multi)
+  1
+  2
+  3)
 
 (display (multi))

src/test/run-pass/nested-defs.scm

@@ -6,15 +6,14 @@
 (define (sqrt x)
   (define (sqrt-iter guess x)
     (define (good-enough? guess x)
-      (define (square x) (* x x))
+      (define (square x)
+        (* x x))
       (< (abs (- (square guess) x)) 0.001))
     (define (improve guess x)
       (define (average x y)
         (/ (+ x y) 2))
       (average guess (/ x guess)))
-    (if (good-enough? guess x)
-        guess
-        (sqrt-iter (improve guess x) x)))
+    (if (good-enough? guess x) guess (sqrt-iter (improve guess x) x)))
   (sqrt-iter 1.0 x))
 
 (display (sqrt 2))

src/test/run-pass/r7rs-spec/4-1-6-Assignments.scm

@@ -0,0 +1,4 @@
+(define x 2)
+(display (+ x 1))
+(set! x 4)
+(display (+ x 1))

src/test/run-pass/sqrt.scm

@@ -4,9 +4,7 @@
 ; http://sarabander.github.io/sicp/html/1_002e1.xhtml#g_t1_002e1_002e7
 
 (define (sqrt-iter guess x)
-  (if (good-enough? guess x)
-      guess
-      (sqrt-iter (improve guess x) x)))
+  (if (good-enough? guess x) guess (sqrt-iter (improve guess x) x)))
 
 (define (improve guess x)
   (average guess (/ x guess)))
@@ -14,7 +12,8 @@
 (define (average x y)
   (/ (+ x y) 2))
 
-(define (square x) (* x x))
+(define (square x)
+  (* x x))
 
 (define (good-enough? guess x)
   (< (abs (- (square guess) x)) 0.001))

src/tests.rs

@@ -18,7 +18,7 @@ upstream for this
 fn run_pass() {
     let manifest_dir = Path::new(env!("CARGO_MANIFEST_DIR"));
 
-    insta::glob!("test/run-pass/**.scm", |p| {
+    insta::glob!("test/run-pass/**/*.scm", |p| {
         let p = PathBuf::from(
             p.canonicalize()
                 .unwrap()

src/value.rs

@@ -1,16 +1,32 @@
-use crate::{ast, eval, prims};
+use crate::{eval, prims};
 use std::rc::Rc;
 
-#[derive(Clone)]
+#[derive(Clone /*, debug2::Debug*/)]
 crate enum Value {
     Num(f64),
-    Func(prims::Func),
-    Lambda(ast::Lambda),
+    // TODO: implement debug2::Debug for `fn` type, and do it right
+    // https://godbolt.org/z/vr9erGeKq
+    Func(prims::NativeFunc),
+    Lambda(eval::Lambda),
     Bool(bool),
     /// Result of things that shouldnt have values, like (define x 3)
+    /// TODO: Figure this out
     Trap,
 }
 
+impl std::fmt::Debug for Value {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Num(arg0) => f.debug_tuple("Num").field(arg0).finish(),
+            // We cant just pass the field because of livetime bs, see https://godbolt.org/z/vr9erGeKq
+            Self::Func(_) => f.debug_struct("Func").finish_non_exhaustive(),
+            Self::Lambda(arg0) => f.debug_tuple("Lambda").field(arg0).finish(),
+            Self::Bool(arg0) => f.debug_tuple("Bool").field(arg0).finish(),
+            Self::Trap => write!(f, "Trap"),
+        }
+    }
+}
+
 impl PartialEq for Value {
     fn eq(&self, other: &Self) -> bool {
         use Value::*;
@@ -18,7 +34,9 @@ impl PartialEq for Value {
             (Num(l), Num(r)) => l == r,
             (Func(l), Func(r)) => *l as usize == *r as usize,
             (Bool(l), Bool(r)) => l == r,
-            (Lambda(l), Lambda(r)) => Rc::ptr_eq(&l.0, &r.0) && Rc::ptr_eq(&l.1, &r.1),
+            (Lambda(l), Lambda(r)) => {
+                Rc::ptr_eq(&l.func, &r.func) && Rc::ptr_eq(&l.captures, &r.captures)
+            }
 
             (Num(_), _) => false,
             (Func(_), _) => false,
@@ -30,10 +48,10 @@ impl PartialEq for Value {
     }
 }
 
-impl std::fmt::Debug for Value {
+impl std::fmt::Display for Value {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            Self::Num(n) => n.fmt(f),
+            Self::Num(n) => std::fmt::Debug::fmt(n, f), // TODO: Change to displays
             Self::Func(_) => f.write_str("#<procedure>"),
             Self::Lambda(_) => f.write_str("#<procedure>"),
             Self::Bool(b) => f.write_str(if *b { "#t" } else { "#f" }),
@@ -51,14 +69,11 @@ impl Value {
         }
     }
 
-    crate fn as_func(&self) -> Result<eval::Callable, eval::RTError> {
+    crate fn as_func(self) -> Result<eval::Callable, eval::RTError> {
         match self {
-            Self::Func(f) => Ok(eval::Callable::Func(*f)),
+            Self::Func(f) => Ok(eval::Callable::Func(f)),
             Self::Lambda(l) => Ok(eval::Callable::Lambda(l)),
-            _ => Err(eval::RTError(format!(
-                "Expected a function, got {:?}",
-                self
-            ))),
+            _ => Err(eval::RTError(format!("Expected a function, got {}", self))),
         }
     }