[Haskell-cafe] Equality constraints in type families

[Wolfgang Jeltsch]

Am Donnerstag, 27. März 2008 23:12 schrieben Sie:
> The reason for the braces in type families is because type indices are
> treated differently than normal parameters. I don't think this should be
> adopted for type synonyms either.
>
> Cheers,
> hugo

In a way, there is also different treatment in the case of type synonyms.  If 
you have the definition

    type ReaderWriterT m = ReaderT (WriterT m),

you cannot leave out the m but you can leave out the result type parameter.

I think, it would be good if the syntax of type synonyms and type synonym 
families was consistent.

Best wishes,
Wolfgang