On 09/07/2012 17:32, Mikhail Vorozhtsov wrote:
On 07/09/2012 09:49 PM, Simon Marlow wrote:
On 09/07/2012 15:04, Mikhail Vorozhtsov wrote:
and respectively
\case P1, P2 -> ... P3, P4 -> ...
as sugar for
\x y -> case x, y of P1, P2 -> ... P3, P4 -> ...
That looks a bit strange to me, because I would expect
\case P1, P2 -> ... P3, P4 -> ...
to be a function of type (# a, b #) -> ... Hm, maybe I put it slightly wrong. Desugaring is really only a means of implementation here.
I think the desugaring is helpful - after all, most of the syntactic sugar in Haskell is already specified by its desugaring. And in this case, the desugaring helps to explain why the multi-argument version is strange.
Would you still expect tuples for \case if you didn't see the way `case x, y of ...` was implemented (or thought that it is a primitive construct)?
Yes, I still think it's strange. We don't separate arguments by commas anywhere else in the syntax; arguments are always separated by whitespace. Cheers, Simon