Converting to arbitrary base from base 10.

ConvertBases.elm

import Graphics.Element exposing (..)
import String 
import Result
import Maybe exposing (withDefault)

main = show (toBase 5 147)

toBase: Int -> Int -> Int
toBase base number =
  toBase' base "" number
  |> String.toInt
  |> Result.toMaybe
  |> withDefault 0


toBase': Int -> String -> Int -> String
toBase' base remainders number = 
  let (divisor, remainder) = getDivisorAndRemainder base number
      remainders' = String.append (toString remainder) remainders 
  in case divisor of
    0 -> remainders'
    _ -> toBase' base remainders' divisor

  
getDivisorAndRemainder: Int -> Int -> (Int, Int)
getDivisorAndRemainder base number = 
  let divisor = floor ((toFloat number) / (toFloat base))
      remainder = number - (divisor * base)
  in
    (divisor, remainder)