[Haskell-cafe] Is it possible to represent such polymorphism?
Du Xi
sdiyazg at sjtu.edu.cn
Sun Oct 2 15:04:10 CEST 2011
--I tried to write such polymorphic function:
expand (x,y,z) = (x,y,z)
expand (x,y) = (x,y,1)
--And it didn't compile. Then I added a type signature:
expand::a->b
expand (x,y,z) = (x,y,z)
expand (x,y) = (x,y,1)
--It still didn't compile. I think the reason is that the following is
disallowed:
f::a->b
f x = x
--Is it possible to get around this and write the "expand" function?
Of course, x and y may be of different types
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