[Haskell-cafe] Type conversion problems

Christian Hofer Christian.Hofer at gmx.de
Sun Jun 13 07:04:42 EDT 2004


Am 13.06.2004 um 12:25 schrieb Lauri Alanko:
>
> Why do you have all those type annotations? Simply writing directly:
>
> fac n = product [1..n]
> term x n = -1 ** n * (x ** (2 * n + 1)) / fac (2 * n + 1)
>
> gives you functions for which are inferred the types (which you can of
> course also give explicitly if you want):
>
> fac :: (Enum a, Num a) => a -> a
> term :: (Floating a, Enum a) => a -> a -> a
>

I didn't expect it to be that easy! Thank you for your detailed answer.

I think, I just didn't expect [1..3.4] to work, but it actually does! 
And I see, I really have to give chapter 12.4 in HSoE a closer look...

Chris



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