TypeFamilies vs. FunctionalDependencies & type-level recursion

AntC anthony_clayden at clear.net.nz
Fri Jun 8 03:00:26 CEST 2012


Simon Peyton-Jones <simonpj at ...> writes:

> 
> I have expanded the draft spec on
> http://hackage.haskell.org/trac/ghc/wiki/NewAxioms

Thanks Simon, that's much clearer.

By the way, are the examples for the multi- type instance declarations quite 
as intended? The heads have no head, as it were. Did you mean, or is this 
allowed?

    type instance F [a] where ...

    type instance F (a, b) where ...

(From a documentation point of view, this shows that the instance groups are 
non-overlapping.)

> to answer some of the questions on AntC’s discussion page.
>  

(I'd rather you called it just *the* discussion page; I'm doing the ego-less 
contributor thing. I must admit that after I got the page started, I've not 
had so much time to keep building it.)

AntC




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