CODEWITHSUNDEEP
haskellfunctional-programming
POC
POC

Reputation: 3

Haskell 2^n functional programming

I am trying to do Haskell version of 2^n integer list. numsFrom generate infinite sequence, I want to map this sequence into number 2, but I have an error message:

Possible cause: ‘map’ is applied to too many arguments.

numsFrom :: Int -> [Int]
numsFrom n = n : numsFrom (n+1)

powerOf2 :: Int -> [Int]
powerOf2 = map(^numsFrom 1) 2

Upvotes: 0

Views: 352

Answers (1)

José Antonio Riaza Valverde
José Antonio Riaza Valverde

Reputation: 747

powerOf2 signature must be powerOf2 :: [Int]. numsFrom returns a list to be mapped, so the function to map is (2^):

powerOf2 :: [Int]
powerOf2 = map (2^) (numsFrom 1)

PD: Note that you don't need numsFrom function:

powerOf2 :: [Int]
powerOf2 = map (2^) [1..]

Upvotes: 1

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