fork download

{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances #-}
 
class PipeFirst b f | f -> b where
 (|>) :: f -> (b -> c) -> c
 
instance PipeFirst b (a -> b) where
 (|>) = flip (.)
 
instance PipeFirst c (a -> b -> c) where
 (|>) = flip ((.).(.))
 
instance PipeFirst d (a -> b -> c -> d) where
 (|>) = flip ((.).(.).(.))
 
main = print $ (f |> g) 1 2 3
 where f x y z = x + y + z
       g = (*2)
 

[1 of 1] Compiling Main             ( prog.hs, prog.o )

prog.hs:6:10:
    Functional dependencies conflict between instance declarations:
      instance PipeFirst b (a -> b) -- Defined at prog.hs:6:10
      instance PipeFirst c (a -> b -> c) -- Defined at prog.hs:9:10
      instance PipeFirst d (a -> b -> c -> d) -- Defined at prog.hs:12:10

prog.hs:9:10:
    Functional dependencies conflict between instance declarations:
      instance PipeFirst c (a -> b -> c) -- Defined at prog.hs:9:10
      instance PipeFirst d (a -> b -> c -> d) -- Defined at prog.hs:12:10

Standard output is empty