{- |
Module : Time.Utils
License : BSD-style
Copyright : (c) 2014 Vincent Hanquez <vincent@snarc.org>
Stability : experimental
Portability : unknown
Some padding / formatting functions.
-}
module Time.Utils
( pad2
, pad3
, pad4
, padN
) where
-- | Pad a non-negative integer modulo 100 to 2 digits.
pad2 :: (Show a, Ord a, Num a, Integral a) => a -> String
pad2 v
| v < 0 = undefined
| v >= 100 = pad2 (v `mod` 100)
| v >= 10 = show v
| otherwise = '0' : show v
-- | Pad a non-negative integer less than 1,000 to 3 digits.
pad3 :: (Show a, Ord a, Num a, Integral a) => a -> String
pad3 v
| v >= 1000 = undefined
| v >= 100 = show v
| v >= 10 = '0' : show v
| otherwise = '0':'0': show v
-- | Pad a non-negative integer to at least 4 digits.
pad4 :: (Show a, Ord a, Num a, Integral a) => a -> String
pad4 v
| v < 0 = undefined
| v >= 1000 = show v
| v >= 100 = '0' : show v
| v >= 10 = '0':'0' : show v
| otherwise = '0':'0':'0': show v
-- | Pad a non-negative integer to at least N digits.
--
-- If the number is greater, no truncation happens.
padN :: (Show a, Ord a, Num a, Integral a) => Int -> a -> String
padN n v
| v < 0 = undefined
| vlen >= n = vs
| otherwise = replicate (n - vlen) '0' ++ vs
where
vs = show v
vlen = length vs