compilation of pattern-matching?

[Simon Marlow]

Lennart Augustsson wrote:
> Sorting by constructor tag is perfectly safe when done right.
> You can read about how to do it in my 1985 FPCA paper or in Simon's book.
> 
> When pattern matching against against things that that are not
> constructors (like literals etc) it's much trickier to reorder them
> since you have to prove harder pattern commutation properties.
> 
> I don't think there is any controversy at all about Haskell pattern
> matching semantics.
> As you say, it's pretty clearly spelled out.
> (It wouldn't hurt to have it written down as a denotational semantics, though.)
> 
> And ghc happens to have a bug.

Just thought I'd mention this other bug in the same area:

   http://hackage.haskell.org/trac/ghc/ticket/246
   (Wrong pat-match order for records)

Cheers,
	Simon