Better letrec reductions.HEADtrunk

However... this is now no longer doing capture-avoiding substitution for
letrecs... and making the variable the redex kinda makes it harder to do
the substitution...

Maybe it's time to switch to using pointers in variables.

1 files changed, 12 insertions, 9 deletions

diff --git a/discocaml/discocaml.ml b/discocaml/discocaml.ml
index ba407c1..a3f34f7 100644
--- a/discocaml/discocaml.ml
+++ b/discocaml/discocaml.ml
@@ -44,28 +44,31 @@ let handle_request { expr; command } : response =
     let buf = Lexing.from_string expr in
     let expr = Parse.expression buf in
     let expr = expr_of_parsetree expr in
+    let binders = get_binders expr in
 
     let expr_response ?(note : string option) (expr : expr ast) : response =
       `Expr
         {
           expr = show_expr expr;
-          has_redex = Option.is_some (Eval.find_redex_cbn expr);
+          has_redex = Option.is_some (Eval.find_redex_cbn expr binders);
           note;
         }
     in
 
-    let step_with (find_redex : expr ast -> expr index option) (expr : expr ast)
-        : expr ast =
-      match find_redex expr with
-      | Some i -> Eval.reduce expr i
+    let step_with
+        (find_redex : expr ast -> binder_info option array -> expr index option)
+        (expr : expr ast) : expr ast =
+      match find_redex expr binders with
+      | Some i -> Eval.reduce expr binders i
       | None -> failwith "no redex"
     in
-    let run_with (find_redex : expr ast -> expr index option) :
-        expr ast -> expr ast Seq.t =
+    let run_with
+        (find_redex : expr ast -> binder_info option array -> expr index option)
+        : expr ast -> expr ast Seq.t =
       let rec loop (expr : expr ast) : expr ast Seq.t =
         Seq.cons expr (fun () ->
-            match find_redex expr with
-            | Some i -> loop (Eval.reduce expr i) ()
+            match find_redex expr binders with
+            | Some i -> loop (Eval.reduce expr binders i) ()
             | None -> Nil)
       in
       loop