Extract digits from a float

digits.elm

import String exposing (toList)
import Maybe
import List exposing (member)
import Graphics.Element exposing (show)

toChar x = 
  if | x == 0 -> '0'
     | x == 1 -> '1'
     | x == 2 -> '2'
     | x == 3 -> '3'
     | x == 4 -> '4'
     | x == 5 -> '5'
     | x == 6 -> '6'
     | x == 7 -> '7'
     | x == 8 -> '8'
     | x == 9 -> '9'
     | otherwise -> ' '
     
fromChar x = 
  if | x == '0' -> 0
     | x == '1' -> 1
     | x == '2' -> 2
     | x == '3' -> 3
     | x == '4' -> 4
     | x == '5' -> 5
     | x == '6' -> 6
     | x == '7' -> 7
     | x == '8' -> 8
     | x == '9' -> 9
     | otherwise -> -1

digits : Float -> List Int
digits float = 
  let chars : List Char
      chars = toList (toString float)
      
      fromChars : List Char -> List (Maybe Int)
      fromChars chars = case chars of 
        [] -> [ ]
        x :: xs -> 
          if | member x (List.map toChar [0..9]) -> Just (fromChar x) :: fromChars xs
             | x == '.' -> fromChars xs
             | otherwise -> [ Nothing ]
  in 
      List.map (Maybe.withDefault -1) (fromChars chars)