FW: Pattern guards vs. case (was, unfortunately :Re: interesting example of laziness/ghc optimisation)

[Simon Peyton-Jones]

| * * * Ketil Malde <ketil@ii.uib.no> wrote:
| 
| > ut - the converse is not true, is it?  I can write
| > 
| >     ... = case foo of
| >                (Foo f) -> ...
| >                (Bar b) -> ...
| > 
| > ut I can't express that as a pattern-guarded expression, can I?

Check out http://research.microsoft.com/~simonpj/Haskell/guards.html
which is implemented in GHC.  Thus

	f x | Foo a <- x = ...
	     | Bar b <- x = ...



Simon