Have you looked at the proposed view patterns? It seems like it would cover the case you gave here. I don't know if there's work being done in this area though. http://hackage.haskell.org/trac/ghc/wiki/ViewPatterns //Gundberg
Hi, Lately I have been using pattern guards more than usual and I find that occasionally I need to nest them (i.e., I have alternatives with a common prefix). This seems to happen when I need to do some preliminary checking, followed by some decision making. Here is an example:
server text | Just xs <- parse text , | "field1" `elem` xs = ... do one thing ... | "field2" `elem` xs = ... do something else ...
server _ = ... invalid request ...
As far as I can see this should be a fairly simple change to the pattern bindings extension. Would anyone else find this a useful feature, and if so what syntax should we use?
-Iavor _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell