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

13 Jan 2008


      On 13 Jan 2008, at 5:49 PM, Achim Schneider wrote:
...
Jonathan Cast  wrote:
...
On 13 Jan 2008, at 5:27 PM, Achim Schneider wrote:
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Answer #2:
Because you can't write
f x = case x of
  [] -> [1]
        -> sort.nub
But why not?
Because arities aren't lifted to the longest argument list.
I think you lost the point of my question...
...
...
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.
What about
f x = [1]
f - = sort.nub
?
You could also do things like
f - x = (foo x).bar
with it. No more rewriting of pointfree code because of added
arguments...
So `-' as a pattern means `implicitly apply the RHS to whatever this  
pattern matches'?  I like it.

jcc