Pretty print Persistent debug SQL statements

pretty-print-sql.hs

#!/usr/bin/runghc -Wall

-- Trivial little script to pretty-print safe SQL from Yesod's logging mechanism.
-- It can be run simply using:
--      prety-print-sql.hs <SQL statement string>

import System.Environment (getArgs, getProgName)
import System.Exit (exitSuccess)


main :: IO ()
main = do
    text <- getArgs
    case text of
        [] -> usageExit
        _ -> do
                putStrLn ""
                putStrLn . sanitize $ unwords text
                putStrLn ""


sanitize :: String -> String
sanitize ('\\' : 'n' : xs) = '\n' : sanitize xs
sanitize ('S':'E':'L':'E':'C':'T' : xs) = "\nSELECT" ++ sanitize xs
sanitize (' ' : 'I':'N':'N':'E':'R': xs) = "\n    INNER" ++ sanitize xs
sanitize (' ' : 'A':'N':'D' : xs) = "\n    AND" ++ sanitize xs
sanitize (' ' : '[' : xs) = "\n  [" ++ sanitize xs
sanitize (x : xs) = x : sanitize xs
sanitize [] = []


usageExit :: IO a
usageExit = do
    pname <- getProgName
    mapM_ putStr
        [ pname,  " : Pretty print an escaped Yesod SQL statement to stdout.\n"
        , "\n"
        , "Usage :\n"
        , "     ", pname, " <SQL statement string>"
        , "\n\n"
        ]
    exitSuccess