the MPTC Dilemma (please solve)

Lennart Augustsson lennart at
Sat Mar 18 20:05:03 EST 2006

I have to agree with Manuel.  I write a lot of Haskell code.
People even pay me to do it.  I usually stay with Haskell-98,
and I don't think it's a great hardship.  Sure, there's fancy
stuff I can't do then, but I'd much rather have a well understood
somewhat less powerful language.

I think the right way forward is more along the lines of
associated type and type level functions rather than
MPTC and FDs.

	-- Lennart

Manuel M T Chakravarty wrote:
> Claus Reinke:
>> however, the underlying problem is not limited to MPTCs, and FDs 
>> are not the only attempt to tackle the problem. so I agree with Isaac: 
>> getting a handle on this issue is imperative for Haskell', because it will 
>> be the only way forward when trying to standardize at least those of 
>> the many extensions that have been around longer than the previous 
>> standard Haskell 98. and if Haskell' fails to do this, it fails.
> Please keep things in perspective:
> (A) It's not as if every interesting program (or even the majority of
> interesting programs) use(s) MPTCs.
> (B) I don't think the time for which an extension has been around is
> particularly relevant.  One of the big selling points of Haskell is that
> it's quite well defined, and hence, its semantics is fairly well
> understood and sane - sure, there are dark corners, but compared to
> other languages of the same size, we are in good shape.  If we include
> half-baked features, we weaken the standard.
> In fact, it's quite worrying that FDs have been around for so long and
> still resisted a thorough understanding.
> Manuel
> _______________________________________________
> Haskell-prime mailing list
> Haskell-prime at

More information about the Haskell-prime mailing list