On 06-Dec-1999, Alex Ferguson <[EMAIL PROTECTED]> wrote:
>
> Now that rank-2 polymorphism seems to be part of the 'received standard'
> (at least two implementations support 'em, and I assume they're a shoo-in
> for Haskell 2), couldn't we really also do with type application?
> It seems that ambiguity is here to stay in Haskell, and in principle
> R2L makes the situation (at least as regards "uninferability") worse.
> But it also provides at least a partial solution: when one has to
> disambiguate a subexpression, as opposed to a top-level def., in several
> cases I've been bitten by, it would have been more concise to remove
> the ambiguity with a type-ap, than by supplying a complete signature.
>
> I'd suggest a syntax for this, but I shall refrain, on account of
> a) not having thought of one, and b) having an uneasy feeling I've
> missed something obvious and am about to have this suggestion shot
> down in flames.
I'm not sure what you mean by type application in this context.
Could you explain in more detail what you mean, or give some reference?
But anyway, the recent proposal for partial type declarations would solve
the practical problem that you have encountered, wouldn't it?
I presume that proposal would apply to type annotations wherever they occur,
including type annotations on sub-expressions.
A couple of different syntaxes were proposed.
One was using underscores for "don't-care" type variables,
the other was using a different qualifier, ":<=" rather than "::",
for partial type qualifiers.
--
Fergus Henderson <[EMAIL PROTECTED]> | "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh> | of excellence is a lethal habit"
PGP: finger [EMAIL PROTECTED] | -- the last words of T. S. Garp.
