On 05/04/2008, Paul Johnson <[EMAIL PROTECTED]> wrote: > myProblem :: (ArrowXml a) -> a XmlTree String > myProblem = proc xml do > name <- getAttrValue "name" -< xml > fmt <- arr lookupFormatter -< name > fmt -< xml >
GHC has a special syntax for using ArrowApply (which HXT is an instance of). Whenever the expression to the left of -< needs to involve a local variable, you can replace -< with -<< and it should work. To understand better what it means, you can read http://www.haskell.org/ghc/docs/latest/html/users_guide/arrow-notation.html -- it's basically just a shorthand for using 'app'. > myProblem :: (ArrowXml a) -> a XmlTree String > myProblem = proc xml do > name <- getAttrValue "name" -< xml > fmt <- arr lookupFormatter -< name > fmt -<< xml Try that and see how it goes. - Cale _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
