A Year in Clojure

Re:A Year in Clojure by StreamBright on Sunday October 07, 2018 @01:03PM (#18161552)

The signature is not really helpful. Can you show me how do you implement the actual function?

If you have operators that are typed like + and +. how can you make this work with Num?

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Re:A Year in Clojure by ff_ on Sunday October 07, 2018 @01:16PM (#18161603)

Also the + operator is typed with Num; from a Haskell repl:

  λ> :t (+)
  (+) :: Num a => a -> a -> a

In case of average we need /:

  λ> :t (/)
  (/) :: Fractional a => a -> a -> a

So our type is going to be constrained by Fractional instead of Num). So an implementation could be (from here [1]):

  import Data.List
  average :: (Real a, Fractional b) => [a] -> b
  average xs = realToFrac (sum xs) / genericLength xs

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