Re: [Haskell-cafe] Beginners arrow question

2008-04-05 Thread Claude Heiland-Allen
Paul Johnson wrote: I'm using arrows for the first time, with HXT. I think I'm getting the hang of it, but one problem has me stumped. I have a function lookupFormatter which takes a string and returns an arrow, and I want to use that arrow. Something like this: myProblem :: (ArrowXml a)

Re: [Haskell-cafe] Beginners arrow question

2008-04-05 Thread Cale Gibbard
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

Re: [Haskell-cafe] Beginners arrow question

2008-04-05 Thread Luke Palmer
On Sat, Apr 5, 2008 at 4:00 PM, Cale Gibbard [EMAIL PROTECTED] wrote: 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