haskell-prime-bounces@haskell.org wrote:
suggestion: undo removal of guards from lambdas, especially (but not only) if pattern guards make it into the language.
See the existing proposals http://hackage.haskell.org/trac/haskell-prime/wiki/LambdaCase http://hackage.haskell.org/trac/haskell-prime/wiki/MultiWayIf
thanks. I'm a fan of the correspondence principle, and as we have a LetCase, there should be a LambdaCase as well (the other seems to be inspired by Lisp's cond?). but the syntax is slightly awkward. is there a reason not to merge LambdaCase and Lambda, thus addressing both my suggestion and the LambdaCase proposal?
f <pat> | <patguard> = <rhs>
\ <pat> | <patguard> -> <rhs>
case x of <arms>
(\ <arms> ) x
claus
ps. strawpoll-2 has both LambdaCase and MultiWayIf as 'no'. but that is numbers, not rationale..
I find LambdaCase quite distasteful, mostly for the same reason that the 'f _ x' syntax for a section is ugly: its just hard to read, because you have to backtrack and re-read the expression when you figure out that there was an implicit lambda lurking earlier. MultiWayIf was my proposal, but I voted against it(!) mainly because (a) it isn't implemented anywhere, and (b) I'm beginning to feel that we don't *really* need any more syntax, at least not when the payoff is small like this. As for extending lambda to allow multiple guards and/or multiple pattern matches, I don't think we need that either. Lambda is a quiet syntax and will be lost at the beginning of a sequence of pattern matches/guards; it's best used for simple lambda expressions, complicated pattern matches should be done using function equations. Cheers, Simon