gistfile1.hs

{-# LANGUAGE OverloadedStrings #-}
module Main where

import Data.List.NonEmpty (NonEmpty((:|)))
import qualified Data.List.NonEmpty as NEL
import Data.Monoid ((<>))
import qualified Data.Text as T
import Data.Text (Text)

chars :: NonEmpty Char
chars = NEL.fromList $ filter (not . (`elem` "OolI"))
  $  ['0'..'9']
  <> ['a'..'z']
  <> ['A'..'Z']

convert :: NonEmpty Char -> Int -> Int -> Text
convert chars width = pad . convert'
  where
    convert' 0 = T.singleton $ zero
    convert' i = T.unfoldr step i
    zero       = NEL.head chars
    highest    = NEL.length chars
    pad        = T.justifyRight width zero
    step 0     = Nothing
    step x     = Just $
      ( (chars NEL.!! (x `mod` highest))
      , x `div` highest
      )

λ> traverse_ (print . convert chars 5) [1..60]
"00001"
"00002"
"00003"
"00003"
"00004"
"00005"
"00006"
"00007"
"00008"
"00009"
"0000a"
"0000b"
"0000c"
"0000d"
"0000e"
"0000f"
"0000g"
"0000h"
"0000i"
"0000j"
"0000k"
"0000m"
"0000n"
"0000p"
"0000q"
"0000r"
"0000s"
"0000t"
"0000u"
"0000v"
"0000w"
"0000x"
"0000y"
"0000z"
"0000A"
"0000B"
"0000C"
"0000D"
"0000E"
"0000F"
"0000G"
"0000H"
"0000J"
"0000K"
"0000L"
"0000M"
"0000N"
"0000P"
"0000Q"
"0000R"
"0000S"
"0000T"
"0000U"
"0000V"
"0000W"
"0000X"
"0000Y"
"0000Z"
"00001"
"00011"
"00021"