On Thu, Nov 5, 2009 at 10:59 AM, Stefan Monnier
We could really use a case statement in which we skip the scrutinee and make (case of {})' be syntactic sugar for `(\x -> case x of {})'.
So we could write:
myFunc = anotherFunc $ case of Left err -> print err Right msg -> putStrLn msg
A minor syntactical addition, a big win!
Since this "case" really defines a function, it seems like it would make more sense to allow defining anonymous functions by pattern matching. I.e. instead of "case of", I think it should use "λ", "\", "fn", or ...
The problem with all of those options is that they introduce a new keyword into the language and can potentially break existing code. Eugene's \{ } avoids that by using a different hole in the grammar, but at the expense of 'un-Haskelly' braces. That and I question how easy it would be to get to parse, because a common idiom seems to be to parse patterns as expressions before converting them to patterns to avoid certain other ambiguities in the grammar, so this requires a { } expression, which may introduce a lot more ambiguity and problems to the grammar than it would seem at first glance. -Edward Kmett