[Haskell-beginners] Partial Loading and Debugging with GHCI

[Alexander Dunlap]

On Thu, Apr 16, 2009 at 8:34 PM, Edward Z. Yang <ezyang at mit.edu> wrote:
> On Thu, 16 Apr 2009, aditya siram wrote:
>>
>> I'm curious as to how one would go about debugging the following program:
>
> Alternatively, instead of trying to find out what the type is (which
> might something completely unintelligible and unhelpful, due to
> Haskell's type inferencing), use :: liberally on subexpressions to say
> "I think the type here should be *blah*"; it will let you zoom in on the
> compiler-human mismatch much more quickly. I think this is one of the
> best ways of Haskell debugging.
>
> Cheers,
> Edward
> _______________________________________________

I use this technique a lot. By telling the compiler more and more
about what you think out to be going on, you can ascertain much more
quickly where you disagree with the compiler.

Alex