[Haskell-cafe] Proof of concept of explanations for instance resolution

Tom Ellis tom-lists-haskell-cafe-2013 at jaguarpaw.co.uk
Thu Oct 27 07:56:56 UTC 2016

On Wed, Oct 26, 2016 at 05:53:31PM -0700, Michael Sloan wrote:
> When typeclass machinery gets complicated, it can be hard to figure interpret
> the meaning behind GHC's messages. In particular "Could not deduce ..." messages
> often reference constraints that are deep in a tree of resolving typeclasses. I
> think it would be great if GHC provided additional information for this
> circumstance. In a way what we need is a "stack trace" of what GHC was thinking
> about when yielding these type errors.
> Thanks for reading!  I hope we can address this UI concern in the future.  I
> hope I've contributed something by demonstrating the possibility!

I think a "stack trace" of what GHC was thinking would be a great idea!  I
brought this idea here:



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