Re: [Haskell-cafe] All equations must have the same arity - why?

That eta-expansion desugaring would lose sharing. Offhand, I don't know of a desugaring that would do the trick and preserve sharing. Any ideas? - Conal On Jan 13, 2008 3:12 PM, Neil Mitchell wrote:

Hi,

It's nice to write functions in point free style:

f = sort . nub

But sometimes I have to add an extra case, on a certain value:

f [] = [1] f = sort . nub

But now these equations have different arities, and its rejected by Haskell. Why does this not simply desugar to:

f [] = [1] f x = (sort . nub) x

i.e. lift the arities to the longest argument list.

Is there a reason this isn't done?

Thanks

Neil _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe