Is it time to start deprecating FunDeps?

AntC anthony_clayden at
Tue Apr 30 11:24:03 CEST 2013

> Roman Cheplyaka <roma at ...> writes:
> 1. What do you mean by deprecating? Deprecate it in GHC? What does it
>    have to do with Haskell'?
> 2. What do you gain by doing so?

GHC is the de facto testing ground for ideas 'on the menu' for Haskell'.
H' has been in paralysis for years around MPTC, Overlaps, FunDeps/Type 
Families (functions). I'm trying to see a way to remove one of the options 
so that we can simplify the choices/move the logjam.

So yes, I mean deprecate in GHC.

> 3. How do you translate cyclic dependencies?

You can get an equivalent to cyclic dependencies using equality 
constraints. (I'll reply to Oleg's example of Sum.) But I agree that my 
mechanical translation doesn't usually get you to the result.

So my GSOC project idea would be to see how far you might get with a more 
sophisticated translation. 


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