Re: Call to arms: lambda-case is stuck and needs your help

On 07/05/2012 10:22 PM, wagnerdm@seas.upenn.edu wrote:

Quoting Mikhail Vorozhtsov :

...

After 21 months of occasional arguing the lambda-case proposal(s) is in danger of being buried under its own trac ticket comments. We need fresh blood to finally reach an agreement on the syntax. Read the wiki page[1], take a look at the ticket[2], vote and comment on the proposals!

P.S. I'm CC-ing Cafe to attract more people, but please keep the discussion to the GHC Users list.

[1] http://hackage.haskell.org/trac/ghc/wiki/LambdasVsPatternMatching [2] http://hackage.haskell.org/trac/ghc/ticket/4359

Well, for what it's worth, my vote goes for a multi-argument \case. I find the comment on the wiki page about mistyping "\case Just x" instead of "\case (Just x)" a lot a bit disingenuous, since you already need these parens with today's lambda. The complaint that multi-argument cases are unorthodox doesn't really hold a lot of weight with me -- much more serious things than syntax have changed in GHC compared to the Report! \case does /not/ require parentheses. I wrote about forgetting them when using MultiClauseLambdas, e.g.

\(A b) -> ... -- \ here reminds me to use () (C d) -> ... ... Y z -> ... -- After a while I forget about them because all I see is -- Pat -> Expr, and that's instantly a case-expression -- alternative clause for me. This might as well be just my personal thing.

Is there a more formal way to cast votes...? People are still coming up with new tweaks. I'll write a summary email with the voted (so far) proposals list, maybe it will be easier to go on from there.