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
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
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)
You can't use variables introduced in "proc" anywhere except on the
right side of "-<". OK, you actually can do this, but your arrow
should be an instance of ArrowApply (which means that you don't really
need it at all, since all such arrows are in fact monads). Your
"myProblem" is desugare
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) -> a XmlTree String
