rev-scientific-0.1.0.0: Data/ReversedScientific.hs

-- |
-- Module      :  Data.ReversedScientific
-- Copyright   :  (c) OleksandrZhabenko 2023
-- License     :  MIT
-- Stability   :  Experimental
-- Maintainer  :  oleksandr.zhabenko@yahoo.com
--
-- Provides a function that shows the somewhat "reversed" scientific notation of the big 'Integer' number so that it is easier (more likely exact) to compare at quick glance twe numbers in such a notation by their order and values.

{-# LANGUAGE NoImplicitPrelude #-}

{-# OPTIONS_HADDOCK -show-extensions #-}

module Data.ReversedScientific where

import GHC.Base
import GHC.Num ((-),Integer)
import Text.Show (Show(..))
import Data.List (length,dropWhileEnd)


showBignum :: Int -> Integer -> String
showBignum n x 
  | l0 < 6 = xShow
  | l >= n = mconcat ["e", show (l - 1), "~m", show l0, "~", k1s, ".", k2s, "...", k3s]
  | otherwise = xShow
      where xShow = show x
            l = length xShow
            k = dropWhileEnd (== '0') xShow 
            l0 = length k
            f (p:q:r:s:t:u:v:vs) = f (p:q:r:t:u:v:vs)
            f (p:q:r:s:t:u:_) = ([p], [q, r], [s, t, u])
            (k1s,k2s,k3s) = f k