Converting number base

Question

Is there a platform function that will do the following?

convertBase :: (Num a, Num b) => Int -> Int -> [a] -> [b]

Convert a number

Answer 1

Using the digits package from Hackage:

import Data.Digits (digits, unDigits)

convertBase :: Integral a => a -> a -> [a] -> [a]
convertBase from to = digits to . unDigits from

You can add a fromIntegral in there if you need the input and output types to be different. Also, the Integral constraint makes more sense than Num, since you probably don't want to deal with complex or floating-point digits.