Early abort of pipeline in REPL (#67)

Fixes #66

src/DblParser/Main.ml

@@ -18,6 +18,9 @@ let make_nowhere data =
   }
 
 let rec repl_seq imported () =
+  InterpLib.Error.wrap_repl_cont (repl_seq_main imported) ()
+
+and repl_seq_main imported () =
   flush stderr;
   Printf.printf "> %!";
   let lexbuf = Lexing.from_channel stdin in

src/InterpLib/Error.ml

@@ -40,5 +40,10 @@ let assert_no_error () =
   if !err_counter <> 0 then
     raise Fatal_error
 
+let wrap_repl_cont cont () =
+  let v = cont () in
+  assert_no_error ();
+  v
+
 let reset () =
   err_counter := 0

src/InterpLib/Error.mli

@@ -28,5 +28,10 @@ val report : ?pos:Position.t -> cls:error_class -> string -> unit
   of each phase. *)
 val assert_no_error : unit -> unit
 
+(** Wrap REPL continuation around additional call of [assert_no_error]. This
+  function should be used in transforming REPL continuations (e.g. those
+  stored in [Surface.ERepl]) in each phase that may raise an error. *)
+val wrap_repl_cont : (unit -> 'a) -> unit -> 'a
+
 (** Reset state of reported errors. Used in REPL in case of an error. *)
 val reset : unit -> unit

src/TypeInference/Expr.ml

@@ -160,7 +160,7 @@ let rec check_repl_def_seq ~tcfix env ienv def_seq tp eff =
   in
   let e =
     { T.pos  = Position.nowhere;
-      T.data = T.ERepl(func, tp, eff)
+      T.data = T.ERepl(InterpLib.Error.wrap_repl_cont func, tp, eff)
     } in
   e