[Haskell-beginners] Difference between Char and Data.Char modules

Stephen Tetley stephen.tetley at gmail.com
Thu Jun 14 23:47:51 CEST 2012

Hi Ken

If you don't want GLR parsing (or attribute grammars) the Happy docs
should be fine. GHC uses Happy, though an LR grammar, for its front
end, so regular LR parsing always works.

If you want GLR you might want to search the web to find out who
authored the GLR extension. I'm afraid I've forgotten the person, but
I seem to remember there was a thesis (possibly United Kingdom MSc ?)
accompanying it.

IIRC, the Happy GLR extension seemed to focus on natural language
parsing rather than parsing ambiguous programming languages (Happy is
generally used just to parse programming languages rather than natural
language). The GLR parsing algorithm originally came from Natural
Language Processing but because it handles ambiguity it was adopted by
compiler developers. In practice, industrial strength GLR parsers for
programming languages (e.g. SGLR and the commercial DMS from Semantic
Designs) add a fair amount of kit so they can disambiguate what they
parse and make good parse trees - I don't think Happy's GLR extension
had this.

On 14 June 2012 20:43, Ken Overton <koverton at lab49.com> wrote:
> Thanks; is there a better, more current example that you know of where I might start instead?

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