Re: Chimeric syntax

On Tue, Apr 28, 2009 at 1:09 PM, Max Bolingbroke wrote:

2009/4/28 Scott Michel :

...

This got me to thinking that either ghc has issues or I have some fundamental misunderstanding of Haskell syntax. Or, maybe I should use someone else's grammar.

GHC's parser is over-generous by design. See http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/Parser. A precise description of what is valid Haskell it is certainly NOT, but it will certainly accept any valid Haskell program. This may not be quite what you want for an IDE - but it might be good enough for a first cut.

Actually, given what ghc will accept, I seriously doubt that the LR grammar can ever successfully translate to a LL(*) grammar. Liberal, it may be, but it probably should be valid. I just followed the current parser rules to their ultimate conclusion. I suspect that people would be quite surprised by what Parser.y.pp will actually accept. Basically, my understanding is that a 'let' should not be allowed in a 'class' declaration and yet, ghc is quite happy to allow it. So my understanding is correct, but ghc grammar is (perhaps) too flexible. -scooter PS: Anyone got a multicore Haskell experience they want to share at Supercomputing this year? The guys from Galois did a great job shocking the audience last year.