CODEWITHSUNDEEP
haskelltypesoperator-overloadingfractions
Benjamin Kovach
Benjamin Kovach

Reputation: 3260

How to implement ^ operator in Haskell?

I'm working on creating a bunch of instances for a Fraction data type in Haskell, and I'm wondering if there's a place I would be able to implement the ^ operator.

What I mean is, I've got several instances of various Num types, and within those instances, I define common operations such as +, -, etc.

With that, the data type behaves as a normal number, as I want it to (meaning I can call things like (Frac 1 2) + (Frac 1 4) and get back Frac 3 4)

What I'm trying to do is implement ^ directly. Right now, I've got it defined like this:

(|^|) :: Fraction -> Int -> Fraction
(|^|) f = foldr (*) mempty . flip replicate f

When I try to change the name of the function to ^, I get an error because it conflicts with Prelude's definition of ^. Is there a Num type I can give my Fraction type an instance of to allow me to use the ^ operator on it?

Thanks!

Upvotes: 6

Views: 642

Answers (1)

sepp2k
sepp2k

Reputation: 370172

Prelude.^ is not part of any type class, so the only way you can define your own ^ function would be to hide the one from Prelude.

Note that since the signature of Prelude.^ is (Num a, Integral b) => a -> b -> a, you'll be able to use it on values of your Frac type just fine as long as it's an instance of Num. You just wouldn't be providing your own implementation.

Upvotes: 12

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