On 13 Jan 2008, at 5:27 PM, Achim Schneider wrote:
"Neil Mitchell" <[EMAIL PROTECTED]> 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?
Answer #2:
Because you can't write
f x = case x of
[] -> [1]
-> sort.nub
But why not? Treating case as syntax sugar for a higher-order
function, so that all binding occurrences of lambdas in the unsugared
code are associated with lambdas, is a good thing, and offers a
natural way of desugaring the above, one case at a time.
jcc
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
