first draft loop/recur, seems to work?

src/compiler.rs

@@ -20,6 +20,7 @@ pub enum Op {
     PopN,
     PushBinding,
     Store,
+    StoreAt,
     Load,
     ResetMatch,
     MatchNil,
@@ -67,6 +68,7 @@ impl std::fmt::Display for Op {
             PopN => "pop_n",
             PushBinding => "push_binding",
             Store => "store",
+            StoreAt => "store_at",
             Load => "load",
             MatchNil => "match_nil",
             MatchTrue => "match_true",
@@ -134,7 +136,7 @@ impl Chunk {
             }
             PushBinding | MatchTuple | MatchList | MatchDict | LoadDictValue | PushTuple
             | PushDict | PushList | PushBox | Jump | JumpIfFalse | JumpIfNoMatch | JumpIfMatch
-            | JumpBack | JumpIfZero | MatchDepth | PopN => {
+            | JumpBack | JumpIfZero | MatchDepth | PopN | StoreAt => {
                 let next = self.bytecode[i + 1];
                 println!("{i:04}: {:16} {next:04}", op.to_string());
             }
@@ -319,22 +321,22 @@ impl Compiler {
 
     fn enter_loop(&mut self) {
         self.loop_info
-            .push(LoopInfo::new(self.len(), self.bindings.len()));
+            .push(LoopInfo::new(self.len(), self.stack_depth));
     }
 
     fn leave_loop(&mut self) {
         self.loop_info.pop();
     }
 
-    fn loop_info(&mut self) -> LoopInfo {
+    fn loop_info(&self) -> LoopInfo {
         self.loop_info.last().unwrap().clone()
     }
 
-    fn loop_idx(&mut self) -> usize {
+    fn loop_idx(&self) -> usize {
         self.loop_info.last().unwrap().start
     }
 
-    fn loop_root(&mut self) -> usize {
+    fn loop_root(&self) -> usize {
         self.loop_info.last().unwrap().stack_root
     }
 
@@ -825,57 +827,96 @@ impl Compiler {
                 self.emit_constant(Value::Nil);
             }
             Loop(value, clauses) => {
-                todo!();
                 //algo:
                 //first, put the values on the stack
                 let (Ast::Tuple(members), _) = value.as_ref() else {
                     unreachable!()
                 };
-                for member in members {
+                for (i, member) in members.iter().enumerate() {
                     self.visit(member);
+                    self.emit_op(Op::StoreAt);
+                    self.emit_byte(i);
                 }
                 let arity = members.len();
+                let stack_depth = self.stack_depth;
                 //then, save the beginning of the loop
+                self.emit_op(Op::Load);
                 self.enter_loop();
-                self.emit_op(Op::ResetMatch);
+                self.stack_depth += arity;
                 //next, compile each clause:
                 let mut clauses = clauses.iter();
                 let mut jump_idxes = vec![];
                 while let Some((Ast::MatchClause(pattern, _, body), _)) = clauses.next() {
+                    self.emit_op(Op::ResetMatch);
                     self.scope_depth += 1;
                     let (Ast::TuplePattern(members), _) = pattern.as_ref() else {
                         unreachable!()
                     };
-                    let mut match_depth = arity;
-                    let mut members = members.iter();
-                    while match_depth > 0 {
+                    self.match_depth = arity;
+                    let mut tup_jump_idxes = vec![];
+                    for member in members {
+                        self.match_depth -= 1;
                         self.emit_op(Op::MatchDepth);
-                        self.emit_byte(match_depth - 1);
-                        self.visit(members.next().unwrap());
-                        match_depth -= 1;
+                        self.emit_byte(self.match_depth);
+                        self.visit(member);
+                        self.emit_op(Op::JumpIfNoMatch);
+                        tup_jump_idxes.push(self.len());
+                        self.emit_byte(0xff);
                     }
+                    self.emit_op(Op::Jump);
+                    let jump_idx = self.len();
+                    self.emit_byte(0xff);
+                    for idx in tup_jump_idxes {
+                        self.chunk.bytecode[idx] = self.len() as u8 - idx as u8 - 2;
+                    }
+                    for _ in 0..arity {
+                        self.emit_op(Op::Pop);
+                    }
+                    self.chunk.bytecode[jump_idx] = self.len() as u8 - jump_idx as u8 - 1;
                     self.emit_op(Op::JumpIfNoMatch);
                     let jnm_idx = self.len();
                     self.emit_byte(0xff);
                     self.visit(body);
+                    self.emit_op(Op::Store);
+                    self.scope_depth -= 1;
+                    while let Some(binding) = self.bindings.last() {
+                        if binding.depth > self.scope_depth {
+                            self.bindings.pop();
+                        } else {
+                            break;
+                        }
+                    }
+                    while self.stack_depth > stack_depth + arity {
+                        self.pop();
+                    }
+                    self.stack_depth -= arity;
                     self.emit_op(Op::Jump);
-                    self.emit_byte(0xff);
                     jump_idxes.push(self.len());
+                    self.emit_byte(0xff);
                     self.chunk.bytecode[jnm_idx] = self.len() as u8 - jnm_idx as u8;
                     self.scope_depth -= 1;
                 }
                 self.emit_op(Op::PanicNoMatch);
-
-                // TODO: fix up jump indexes a la match
-
+                for idx in jump_idxes {
+                    self.chunk.bytecode[idx] = self.len() as u8 - idx as u8 - 1;
+                }
+                self.emit_op(Op::PopN);
+                self.emit_byte(arity);
+                self.stack_depth -= arity;
+                self.emit_op(Op::Load);
+                self.stack_depth += 1;
                 self.leave_loop();
             }
-            Recur(_) => {
-                // algo
-                // visit each member of the arguments
-                // then store those in the return register
-                // then pop back to loop stack root
-                // then jump to loop start
+            Recur(args) => {
+                for (i, arg) in args.iter().enumerate() {
+                    self.visit(arg);
+                    self.emit_op(Op::StoreAt);
+                    self.emit_byte(i);
+                }
+                self.emit_op(Op::PopN);
+                self.emit_byte(self.loop_root());
+                self.emit_op(Op::JumpBack);
+                self.emit_byte(self.len() - self.loop_idx());
             }
             Interpolated(..)
             | Arguments(..)
@@ -910,7 +951,7 @@ impl Compiler {
                 }
                 PushBinding | MatchTuple | MatchList | PushTuple | PushDict | PushList
                 | MatchDict | LoadDictValue | PushBox | Jump | JumpIfFalse | JumpIfNoMatch
-                | JumpIfMatch | JumpBack | JumpIfZero | MatchDepth | PopN => {
+                | JumpIfMatch | JumpBack | JumpIfZero | MatchDepth | PopN | StoreAt => {
                     let (_, next) = codes.next().unwrap();
                     println!("{i:04}: {:16} {next:04}", op.to_string());
                 }

src/main.rs

@@ -74,8 +74,15 @@ pub fn run(src: &'static str) {
 pub fn main() {
     env::set_var("RUST_BACKTRACE", "1");
     let src = "
-repeat 4.8 {
-    true
+loop (true) with {
+    (false) -> :done
+    (true) -> recur (42)
+    (42) -> recur (:thingie)
+    (:thingie) -> {
+        let x = false
+        12
+        recur (x)
+    }
 }
     ";
     run(src);

src/value.rs

@@ -25,6 +25,7 @@ impl LFn {
 
 #[derive(Clone, Debug, PartialEq)]
 pub enum Value {
+    Nothing,
     Nil,
     True,
     False,
@@ -44,6 +45,7 @@ impl std::fmt::Display for Value {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
         use Value::*;
         match self {
+            Nothing => write!(f, "_"),
             Nil => write!(f, "nil"),
             True => write!(f, "true"),
             False => write!(f, "false"),
@@ -130,6 +132,7 @@ impl Value {
     pub fn type_of(&self) -> &'static str {
         use Value::*;
         match self {
+            Nothing => unreachable!(),
             Nil => "nil",
             True => "bool",
             False => "bool",

src/vm.rs

@@ -34,7 +34,7 @@ pub struct Vm<'a> {
     pub stack: Vec<Value>,
     pub chunk: &'a Chunk,
     pub ip: usize,
-    pub return_register: Value,
+    pub return_register: [Value; 8],
     pub matches: bool,
     pub match_depth: u8,
     pub result: Option<Result<Value, Panic>>,
@@ -46,7 +46,16 @@ impl<'a> Vm<'a> {
             chunk,
             stack: vec![],
             ip: 0,
-            return_register: Value::Nil,
+            return_register: [
+                Value::Nothing,
+                Value::Nothing,
+                Value::Nothing,
+                Value::Nothing,
+                Value::Nothing,
+                Value::Nothing,
+                Value::Nothing,
+                Value::Nothing,
+            ],
             matches: false,
             match_depth: 0,
             result: None,
@@ -72,7 +81,13 @@ impl<'a> Vm<'a> {
             .map(|val| val.to_string())
             .collect::<Vec<_>>()
             .join("|");
-        println!("{:04}: [{inner}] {}", self.ip, self.return_register);
+        let register = self
+            .return_register
+            .iter()
+            .map(|val| val.to_string())
+            .collect::<Vec<_>>()
+            .join(",");
+        println!("{:04}: [{inner}] ({register})", self.ip);
     }
 
     fn print_debug(&self) {
@@ -174,14 +189,23 @@ impl<'a> Vm<'a> {
                 self.ip += 2;
             }
             Store => {
-                self.return_register = self.pop();
-                self.push(Value::Nil);
+                self.return_register[0] = self.pop();
+                self.push(Value::Nothing);
                 self.ip += 1;
             }
+            StoreAt => {
+                let i = self.chunk.bytecode[self.ip + 1] as usize;
+                self.return_register[i] = self.pop();
+                self.ip += 2;
+            }
             Load => {
-                let mut value = Value::Nil;
-                swap(&mut self.return_register, &mut value);
+                let mut i = 0;
+                while i < 8 && self.return_register[i] != Value::Nothing {
+                    let mut value = Value::Nothing;
+                    swap(&mut self.return_register[i], &mut value);
                     self.push(value);
+                    i += 1;
+                }
                 self.ip += 1;
             }
             ResetMatch => {