Remove SimpleLet

poorly defined semantics wrt environment, more trouble than it's worth

Author: ianzhao

src/cont.rs

@@ -111,10 +111,6 @@ pub enum Cont {
         next: Rc<Expr>,
         cont: Rc<Cont>,
     },
-    SimpleLet {
-        arg: Symbol,
-        cont: Rc<Cont>,
-    },
     Conditional {
         consequent: Rc<Expr>,
         alternate: Option<Rc<Expr>>,

src/evaler.rs

@@ -227,17 +227,6 @@ pub(crate) fn eval_expr(state: State) -> Bouncer {
                         winds,
                     }),
                 },
-                Expr::SimpleLet { arg, value, body } => Bouncer::Bounce(State {
-                    acc: Acc::Expr(value.clone()),
-                    cont: Rc::new(Cont::SimpleLet {
-                        arg: *arg,
-                        cont: Cont::from_body(body, Some(cont)),
-                    }),
-                    env,
-                    rib,
-                    stack,
-                    winds,
-                }),
                 Expr::Undefined => Bouncer::Bounce(State {
                     acc: Acc::Obj(Ok(ObjectRef::Undefined)),
                     cont,
@@ -312,17 +301,6 @@ pub(crate) fn eval_expr(state: State) -> Bouncer {
                         winds,
                     })
                 }
-                Cont::SimpleLet { arg, cont } => {
-                    env.insert(*arg, obj);
-                    Bouncer::Bounce(State {
-                        acc: Acc::Obj(Ok(ObjectRef::Undefined)),
-                        cont: cont.clone(),
-                        env,
-                        rib,
-                        stack,
-                        winds,
-                    })
-                }
                 Cont::Conditional {
                     consequent,
                     alternate,

src/expr.rs

@@ -52,11 +52,6 @@ pub enum Expr {
         value: Rc<Expr>,
     },
     Begin(Vec<Rc<Expr>>),
-    SimpleLet {
-        arg: Symbol,
-        value: Rc<Expr>,
-        body: Vec<ExprOrDef>,
-    },
     Undefined,
 }