Re: [Haskell-cafe] lambda case (was Re: A big hurray for lambda-case (and all the other good stuff))

I had been missing a pattern matching lambda in Haskell for a long time (SML had "fn" since ages) and my typical use will be monadic_expr >>= \case branches I think "\case" is not the worst choice, certainly better than "of" ... Thanks to the GHC 7.6 developers! Cheers, Andreas On 29.11.12 12:49 PM, Jon Fairbairn wrote:

Ben Franksen writes:

...

just wanted to drop by to say how much I like the new lambda case extension. I use it all the time and I just *love* how it relieves me from conjuring up dummy variables, which makes teh code not only esier to write but also to read.

...

[…] should *definitely* go into Haskell'13.

As I was opposed to the suggestion for lambda case I didn’t really follow the discussion of the syntax, but I’m puzzled by the choice. To me it seems obvious that if we are going to do this (as opposed to something more decomposable like lambda-match), we should do it simply by making the “case exp” part of a case expression optional. So the syntax for lambda- case would be

of {alts…}

and we would then describe

case e of {…}

as syntactic sugar for

(of {…}) (e)

Doing it this way doesn’t introduce any new syntactic elements and has fewer tokens at the point of use.

I don’t see any need for a \ in the syntax: this is a functional language we are talking about after all. Once we know that “of” introduces a function, that should be enough.

-- Andreas Abel <>< Du bist der geliebte Mensch. Theoretical Computer Science, University of Munich Oettingenstr. 67, D-80538 Munich, GERMANY andreas.abel@ifi.lmu.de http://www2.tcs.ifi.lmu.de/~abel/