[Haskell-cafe] Parsec - separating Parsing from Lexing

[Fernando Henrique Sanches]

Hi.

I believe I'm using parsec 3.0.1, although I already fixed the imports (even
thou they were working).

Thanks for the references, specially the parsec User Guide - it saved my
life, in 30 minutes I actually *understood* my mistake and fixed it. Now my
code and it compiles and makes sense, even though it's a bit useless, since
it has no return values [yet].

I'll take a look at UUAG and Tiger. However, since this is a simple college
assignment, I want my compiler to be as simple as possible but in a way I
understand what I'm doing, so I'll probably be doing it by hand.

Fernando Henrique Sanches


On Mon, Nov 30, 2009 at 2:58 PM, Stephen Tetley <stephen.tetley at gmail.com>wrote:

> Hi Fernando
>
> Which version of Parsec are you using, the one that ships with GHC or
> Parsec 3?
>
> I would imagine whichever you one you are using you have the imports
> wrong for these modules:
>
> import Text.Parsec.Pos
> import Text.Parsec.Prim
>
> should be ...
>
> import Text.ParserCombinators.Parsec.Pos
> import Text.ParserCombinators.Parsec.Prim
>
>
> Also it seems like an applicative instance for Parsec's GenParser
> monad is missing. This isn't defined for parsec-2.1.0.1, people seem
> to define it themselves:
>
> -- The Applicative instance for every Monad looks like this.
> instance Applicative (GenParser s a) where
>    pure  = return
>    (<*>) = ap
>
> ... you will need `ap` from Control.Monad in scope.
>
> Also there is a pdf document for Parsec (should be available from Daan
> Leijen's home page) that covers separate scanners, it has quite a lot
> more documentation than Parsec's Haddock docs.
>
> For semantic analysis I'd highly recommend UUAG, it is well documented
> and used for a large compiler (EHC). There is also a version of Andrew
> Appel's Tiger language written with it that is much smaller and more
> comprehensible, the version on Hackage doesn't seem to contain the
> attribute grammar source but it is available here:
>
> http://www.cs.uu.nl/wiki/bin/view/HUT/TigerCompiler
>
> http://www.cs.uu.nl/wiki/bin/view/HUT/AttributeGrammarSystem
>
> Best wishes
>
> Stephen
>
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