CODEWITHSUNDEEP
haskell
Diana
Diana

Reputation: 1437

Haskell - sum of cubes of a list

I have to write a function that sums the cubes of a list of numbers.

This is my code so far:

cube' :: (Num a) => a -> a 
cube' x = x*x*x


mySum :: (Num a) => [a] -> a 
mySum [] = []
mySum xs = foldr (\acc x -> acc + cube'(x)) 0 xs

The problem is that when I run it I get the following error:

No instance for (Num[t0]) arising from a use of 'it'

In a stmt of an interactive GHCI command: print it

Upvotes: 0

Views: 705

Answers (1)

Luis Casillas
Luis Casillas

Reputation: 30227

You're definitely on the right track. As bhelkir points out in a comment, the first clause of the definition is wrong and unnecessary. The other problem is that you have the argument order wrong for the lambda.

Upvotes: 1

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