Re: Fw: [Haskell-cafe] IO within parser
I noticed that StateT can enclose IO actions for instance. So you are saying the whole Parsec library would need to be rewritten as something like a ParsecT transformer monad for this to work? If this is the case I suppose I will stick with returning my list of include files. - Greg - Original Message From: Bulat Ziganshin <[EMAIL PROTECTED]> To: Gregory Propf <[EMAIL PROTECTED]> Cc: [email protected] Sent: Saturday, August 11, 2007 11:33:00 PM Subject: Re: Fw: [Haskell-cafe] IO within parser Hello Gregory, Sunday, August 12, 2007, 9:32:04 AM, you wrote: >> I've been struggling with writing a parser that needs to parse include >> files within source files. Parsec can't accomplish with without using unsafePerformIO because it's monad is pure. it's algorithmically impossible to have any i/o actions inside it. there was plans to rewrite Parsec in monad-transformer way and afair it was even one of GSOC projects -- Best regards, Bulatmailto:[EMAIL PROTECTED] Fussy? Opinionated? Impossible to please? Perfect. Join Yahoo!'s user panel and lay it on us. http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7 ___ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Fw: [Haskell-cafe] IO within parser
Hello Gregory, Sunday, August 12, 2007, 9:32:04 AM, you wrote: >> I've been struggling with writing a parser that needs to parse include >> files within source files. Parsec can't accomplish with without using unsafePerformIO because it's monad is pure. it's algorithmically impossible to have any i/o actions inside it. there was plans to rewrite Parsec in monad-transformer way and afair it was even one of GSOC projects -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
Fw: [Haskell-cafe] IO within parser
Well the docs ( http://legacy.cs.uu.nl/daan/download/parsec/parsec.html ) hint that setInput and getInput are good for this. I can certainly how they *would* be - if I knew how to pull in files within the parse. Actually I use those functions to do multiple recursive passes but of course you already have the output from the first pass in the parser there. runParser only *looks* like it takes input from a file. Actually it just parses the string you give it and uses the filename arg for error messages only. You still need a way to pull the data into the string from the file. (Note: I accidentally sent this to Andrew instead of the list originally) - Original Message From: Andrew Coppin <[EMAIL PROTECTED]> To: [email protected] Sent: Saturday, August 11, 2007 1:25:16 PM Subject: Re: [Haskell-cafe] IO within parser Gregory Propf wrote: > I've been struggling with writing a parser that needs to parse include > files within source files. So far I cannot get this to work (in > reality to get work done I wrote a kludge that returns a list of > include filenames to be run later in a pure IO function. I realized > that this just amounted to creating my own half-assed monad system so > I really don't want to use this approach). I have read the tutorials > I could find on monad transformers but I still don't see what's going > on. I'm using the Parsec parser library. Here's an simple example of > what I've tried. I also tried using liftIO and got a message about > needing to add an instance of MonadIO. This made more sense but the > type of liftIO is baffling The fun part is that Parsec already has a feature for include files... (I can't remember where the heck it is or how you use it though.) ___ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe Fussy? Opinionated? Impossible to please? Perfect. Join Yahoo!'s user panel and lay it on us. Choose the right car based on your needs. Check out Yahoo! Autos new Car Finder tool. http://autos.yahoo.com/carfinder/___ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
