[Haskell-cafe] problem with happy
Roman Dzvinkovsky
romand.ne at gmail.com
Tue Oct 26 11:13:31 EDT 2010
lexer works fine, problem is in happy parser.
2010/10/26 Stephen Tetley <stephen.tetley at gmail.com>
> Hello
>
> I would change you Alex specification to this:
>
> $digit = 0-9 -- digits
> $alpha = [a-zA-Z] -- alphabetic characters
> $eol = [\r\n]
> $any = [^$eol]
>
> tokens :-
>
> $eol { tok $ \_ -> Eol }
> $any+ { tok $ \s -> Str s }
>
>
> The complementation operator (^) works of character sets so I don't
> expect your original formulation to work:
>
> $any = [^\r\n]
>
> (maybe it should, but I never liked the Alex syntax...)
>
> You can test alex scanners like this:
>
> demo01 = alexScanTokens "happy?\n"
> demo02 = readFile "sample" >>= print . alexScanTokens
>
> Note - your sample file is using extended characters so it fails for
> me with Alex 2.3.2. I'm now sure how capable the current version of
> Alex is or whether better Unicode support can be enabled with flags.
>
> Regards
>
> Stephen
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