CSE230 Fa16 - swizzle-v2

> import System.Environment
> import Data.Maybe
> import Data.Char

> code = smalls ++ caps 
>   where 
>     smalls   = zip ['a' .. 'z'] shuffles 
>     caps     = zip ['A' .. 'Z'] (map toUpper shuffles) 
>     shuffles = "thequickbrownfxjmpsdvlazyg"

First, we will just make two operations for swizzling and unswizzling characters.

> txChar kvs c  = fromMaybe c (lookup c kvs)
> swizzleChar   = txChar code 
> unswizzleChar = txChar [(y,x) | (x,y) <- code]

To (un/)swizzle one line, we will (un/)swizzle each character on the line. We simply make actual operation a parameter.

> txLine op     = map op

To swizzle a file, we will first reverse the lines in the file and then swizzle each line of the file.

> txContent op  = unlines . map (txLine op) . reverse . lines

To actually transform a file

> txFile op f   = do d  <- readFile f
>                    writeFile (f ++ ".swz") (txContent op d)

And to transform many files

> txFiles op = sequence_ . map (txFile op)

Finally, at the very top, the command line args tell us whether to swizzle or unswizzle

> main = do args <- getArgs 
>           case args of 
>             ("-s":files) -> txFiles swizzleChar files
>             ("-u":files) -> txFiles unswizzleChar files
>             (_)          -> putStrLn "usage: swizzle -s file1 file2 ... OR swizzle -u file1 file2 ..."