parse loop and recur

src/value.rs

@@ -25,10 +25,12 @@ pub enum Value<'src> {
     // ref-counted, immutable, persistent
     List(Vector<Self>),
     // ref-counted, immutable, persistent
+    // dicts may only use keywords as keys
     Dict(HashMap<&'src str, Self>),
     Box(&'src str, Rc<RefCell<Self>>),
     Fn(Rc<Fn<'src>>),
     Base(Base<'src>),
+    Recur(Vec<Self>),
     // Set(HashSet<Self>),
     // Sets are hard
     // Sets require Eq
@@ -57,6 +59,7 @@ impl<'src> Clone for Value<'src> {
             Value::Box(name, b) => Value::Box(name, b.clone()),
             Value::Placeholder => Value::Placeholder,
             Value::Base(b) => Value::Base(b.clone()),
+            Value::Recur(..) => unreachable!(),
         }
     }
 }
@@ -111,6 +114,7 @@ impl<'src> fmt::Display for Value<'src> {
                 };
                 write!(f, "base fn {}", name)
             }
+            Value::Recur(..) => unreachable!(),
         }
     }
 }

src/vm.rs

@@ -482,7 +482,23 @@ pub fn eval<'src, 'a>(
         Ast::Pair(..) => {
             unreachable!()
         }
-        Ast::Loop(_, _) => todo!(),
+        Ast::Loop(init, clauses) => {
-        Ast::Recur(_) => todo!(),
+            let mut args = eval(&init.0, ctx)?;
+            loop {
+                let result = match_clauses(&args, clauses, ctx)?;
+                if let Value::Recur(recur_args) = result {
+                    args = Value::Tuple(Rc::new(recur_args));
+                } else {
+                    return Ok(result);
+                }
+            }
+        }
+        Ast::Recur(args) => {
+            let mut vect = Vec::new();
+            for arg in args {
+                vect.push(eval(&arg.0, ctx)?);
+            }
+            Ok(Value::Recur(vect))
+        }
     }
 }