[Haskell-cafe] lambda case

[Roman Cheplyaka]

It hasn't made it to the standard yet, though. If some experimental
feature is implemented in GHC, it doesn't mean it's set in stone.

I find this discussion useful — there are some interesting points
(splitting "case of" into two parts) that I don't remember reading in the
original thread (but maybe it's just me).

Roman

* Brent Yorgey <byorgey at seas.upenn.edu> [2012-11-30 09:52:53-0500]
> Oh, PLEASE people.  Let's not have another round of bikeshedding about
> this AFTER the feature is already implemented!
> 
> -Brent
> 
> On Fri, Nov 30, 2012 at 01:25:27PM +0100, Herbert Valerio Riedel wrote:
> > Jon Fairbairn <jon.fairbairn at cl.cam.ac.uk> writes:
> > 
> > [...]
> > 
> > > “\case” complicates lambda, using “of” simply breaks “case … of …”
> > > into two easily understood parts.
> > 
> > Just some observation (I'm rather late to the lambda-case discussion, so
> > this might have been already pointed out previously):
> > 
> > if the reserved keyword 'of' was to take the place of '\case', shouldn't
> > then
> > 
> >   'case' exp
> > 
> > w/o the "'of' { alts }"-part become a separately valid expression (with
> > 'case' essentially meaning 'flip ($)') to really break it up into two
> > independent parts? Then 'case exp of { alts }' wouldn't be a special
> > form anymore, but would just result from combining 'case' and 'of';
> > 
> > 'case' wouldn't even need to be a reserved keyword (and thus the grammar
> > could be simplified), if it wasn't for the current grammar which
> > requires to isolate a \case-expression by using () or $, consider e.g.:
> > 
> >   {-# LANGUAGE LambdaCase #-}
> >   
> >   import System.Environment
> >   
> >   case' :: b -> (b -> c) -> c
> >   case' = flip ($)
> >   
> >   main = do
> >     s <- getArgs
> >   
> >     case' s $ \case  -- image '\case' was actually '\of' or 'of'
> >       [x] -> putStrLn ("Hello " ++ x)
> >       _   -> putStrLn "wrong number of arguments given"
> > 
> > 
> > just my 2¢
> > 
> > cheers,
> >   hvr
> > 
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> > 
> 
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