Am Donnerstag 18 März 2010 22:34:48 schrieb Andrew Coppin: > Job Vranish wrote: > > Hoogle is a great tool for finding haskell functions: > > > > http://www.haskell.org/hoogle/ > > > > You can punch in the type of a function you want and it will give you > > a list of functions that might do what you need. > > Generalizing the types a bit usually helps. Searching for either m a > > -> n m a or IO a -> m a would give you 'lift' and 'liftIO' as > > one of the top results. > > Is there a tool anywhere which can figure out how to construct a > function with a specific type signature? Hoogle works if the thing you > seek is a single function, but not so much if you need to throw several > functions together. > > (For example, the signature "x -> [x -> y] -> [y]" can be implemented by > \ x -> map ($ x), but this is initially non-obvious.) >
http://hackage.haskell.org/package/djinn does that, but it has serious limitations (it doesn't know [], and it doesn't accept recursive types, so you can't define a list-type yourself: Djinn> data List a = Nil | Cons a (List a) Error: Recursive types are not allowed: List ) So, no luck with x -> [x -> y] -> [y]. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
