Better error messages on type notation?


Hey reasonml,

Since the release of, I haven’t seen an improvement into error messages and I got a question about them.

While working with Reason you might encounter errors that look like that:

This value might need to be wrapped in a function that takes an extra
  parameter of type string

  Here's the original error message
  This has type:
  But somewhere wanted:
    string => unit

and the only complaint that I have that might save a lot of time for not only new comers it’s to try give as maximum information about the “somewhere”. Giving the filename at least or even the apply where is being used would be a life saver.

This is the error that appears in Elm’s compiler for similar cases:

-- TYPE MISMATCH ---------------------------- Main.elm

The 1st argument to `drop` is not what I expect:

8|   List.drop (String.toInt userInput) [1,2,3,4,5,6]
This `toInt` call produces:

    Maybe Int

But `drop` needs the 1st argument to be:


Hint: Use Maybe.withDefault to handle possible errors.

Let me know if that make sense or if it’s an unchangeable particularity of ocaml’s compiler.