found a bug inside the match translation.

compiler/lcalc/ast.ml

@@ -26,6 +26,7 @@ type lit =
 
 type except = ConflictError | EmptyError | NoValueProvided | Crash
 
+
 type expr =
   | EVar of expr Bindlib.var Pos.marked
   | ETuple of expr Pos.marked list * D.StructName.t option
@@ -118,6 +119,8 @@ let make_letopt_in
   (e2: expr Pos.marked Bindlib.box)
 : expr Pos.marked Bindlib.box =
 
+(* let%opt x: tau = e1 in e2 == matchopt e1 with | None -> None | Some x -> e2 *)
+
   let pos = Pos.get_position (Bindlib.unbox e2) in
 
   let+ e2 = make_abs

compiler/lcalc/compile_without_exceptions.ml

@@ -106,7 +106,16 @@ and translate_expr (ctx : ctx) (e : D.expr Pos.marked) : A.expr Pos.marked Bindl
 
     let e2 =
       let+ e1 = Bindlib.box (A.EVar (x, pos))
-      and+ cases = Bindlib.box_list (List.map (translate_expr ctx) cases) in
+      (* there is an issue here. *)
+      and+ cases = cases
+        |> List.map (fun e' -> translate_expr ctx e')
+        |> List.map (function
+          | A.ESome e'' -> e''
+          | _ -> assert false
+        )
+        |> assert false
+        |> Bindlib.box_list
+      in
       same_pos @@ A.EMatch ((e1, pos), cases, en)
     in
 

compiler/lcalc/to_ocaml.ml

@@ -108,6 +108,7 @@ let avoid_keywords (s : string) : string =
     | "object" | "of" | "open" | "or" | "private" | "rec" | "sig" | "struct" | "then" | "to"
     | "true" | "try" | "type" | "val" | "virtual" | "when" | "while" | "with" ->
         true
+    | "x" -> true (* i need a variable to make the translation *)
     | _ -> false
   then s ^ "_"
   else s
@@ -331,7 +332,7 @@ let rec format_expr (ctx : Dcalc.Ast.decl_ctx) (fmt : Format.formatter) (e : exp
     Format.fprintf fmt "@[<hov 2> Some@ %a@ @]" format_with_parens e1
   | ENone -> Format.fprintf fmt "None@"
   | EMatchopt (e1, e2, e3) ->
-    let x = assert false in
+    let x = Ast.Var.make ("x", Pos.no_pos) in
     Format.fprintf fmt "@[<hov 2>match@ %a@]@ with@\n| None ->@[<hov 2>@ %a@]@\n| Some %a ->@[<hov 2>@ %a@ %a@]" format_expr e1 format_with_parens e2 format_var x format_with_parens e3 format_var x
 
 let format_struct_embedding (fmt : Format.formatter)