[Haskell-cafe] Re: What do _you_ want to see in FGL?

[Henning Thielemann]

On Tue, 11 May 2010, Ivan Lazar Miljenovic wrote:

> Henning Thielemann <lemming at henning-thielemann.de> writes:
>
>> I do not see why there is the need for any type extension, at
>> all. Consider cabal-sort, a very basic program, that is Haskell-98
>> today, will no longer run in Hugs and JHC (untested so far) because it
>> uses FGL's topological sort when FGL upgraded to associated types.
>
> How should it be able to specify a fixed type value for the vertex type?
> We can't specify that g :: * -> * -> * -> * because the vertex type
> should _not_ be a parameter in that sense (since for many graphs it
> won't be, and we need some way of specifying what it is).

If I understand you right, you say that explicit type parameters for 
labels are ok, because I can set them to () if not needed, but for an 
alternative node type you find an explicit type parameter inappropriate?