toBase62 :: Word64 -> String
toBase62 w = showIntAtBase 62 represent w ""
  where
    represent :: Int -> Char
    represent x
        | x < 10 = Char.chr (48 + x)
        | x < 36 = Char.chr (65 + x - 10)
        | x < 62 = Char.chr (97 + x - 36)
        | otherwise = error "represent (base 62): impossible!"
toBase62 :: Word64 -> String
toBase62 w = showIntAtBase 62 represent w ""
  where
    represent :: Int -> Char
    represent x
        | x < 10 = Char.chr (48 + x)
        | x < 36 = Char.chr (65 + x - 10)
        | x < 62 = Char.chr (97 + x - 36)
        | otherwise = error "represent (base 62): impossible!"
toBase62 w = showIntAtBase 62 represent w ""
  where
    represent :: Int -> Char
    represent x
        | x < 10 = Char.chr (48 + x)
        | x < 36 = Char.chr (65 + x - 10)
        | x < 62 = Char.chr (97 + x - 36)
        | otherwise = error "represent (base 62): impossible!"