1 files changed, 13 insertions, 2 deletions
diff --git a/discocaml/eval.ml b/discocaml/eval.ml
index f8f7dc2..a5cfe41 100644
--- a/discocaml/eval.ml
+++ b/discocaml/eval.ml
@@ -15,8 +15,19 @@ let is_redex (ast : expr ast) (i : expr index) : bool =
       | _ -> false)
   | Var _ -> false
 
-let find_redex_cbv_in (_ast : expr ast) (_i : expr index) : expr index option =
-  None
+let find_redex_cbv_in (ast : expr ast) : expr index -> expr index option =
+  let rec loop (i : expr index) : expr index option =
+    or_else
+      (match get_subexpr ast i with
+      | App (f, x) -> or_else (loop f) (lazy (loop x))
+      | Int _ -> None
+      | Lam (_, _) -> None
+      | Prim (Add, (l, r)) | Prim (Sub, (l, r)) | Prim (Mul, (l, r)) ->
+          or_else (loop l) (lazy (loop r))
+      | Var _ -> None)
+      (lazy (if is_redex ast i then Some i else None))
+  in
+  loop
 
 let find_redex_cbn_in (ast : expr ast) : expr index -> expr index option =
   let rec loop (i : expr index) : expr index option =