[Haskell-cafe] Functional dependencies *not* part of the next Haskell standard?

[Donald Bruce Stewart]

bulat.ziganshin:
> Hello Simon,
> 
> Friday, July 13, 2007, 11:37:59 AM, you wrote:
> 
> > | I think the implementation is some 90% complete though, in GHC head.
> > | Certainly you can write many associated types programs already -- the
> > | missing part is finishing off associated type synonyms, iirc.
> 
> > ...and we have a working implementation of that too, thanks to Tom
> > Schrijvers.  It's not in the HEAD yet, but it will be in a few weeks.
> 
> so it will be a part of 6.8? great news! afaiu, ATS, rather than AT,
> is direct substitution for FD?

Functional dependencies desugar to indexed type families, an extension
of the original associated, in GHC head already. For the full story,
see the wiki page.

    http://haskell.org/haskellwiki/GHC/Indexed_types

which includes an example of porting functional dependencies to 
associated types

    http://haskell.org/haskellwiki/GHC/Indexed_types#A_associated_type_synonym_example

-- Don