[gertef]

> I often fill in the implementations after I work out the types.

OK, but that's the opposite of deffering type errors until runtime.

Using "undefined"/bottom as the implemenation of a function is how we wrote Haskell before GHC added support for deferring type-errors.

[ORioN63]

Oops. I still use undefined everywhere, while my code isn't complete.

Also, typed holes. Typed holes are awesome for building implementations based on types.

[willtim]

Yes I don't use deferred type errors much. But the parent poster wanted the option to avoid worrying about type correct programs.