[Haskell-cafe] unary pattern matching
john at repetae.net
Thu Jan 26 21:30:37 EST 2006
On Fri, Jan 27, 2006 at 12:28:23PM +1100, Donald Bruce Stewart wrote:
> > I have often wanted a shorthand syntax for testing if a value matches a
> > given pattern. I want to implement such an extension for jhc but can't
> > decide an appropriate syntax so I thought I'd ask the group. basically I
> > want something like
> > /Left (Just _)/ expands to
> > \x -> case x of
> > Left (Just _) -> True
> > _ -> False
> Something like pattern guards?
> f x | Just _ <- x = putStrLn "something"
hmm.. how about
(| Left (Just _) |)
since | cannot be used as a section so it can be unambigously lexed as a
different symbol. I think I like it. any other ideas?
John Meacham - ⑆repetae.net⑆john⑈
More information about the Haskell-Cafe