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-- |
-- Copyright : (c) 2015 Egor Tensin <Egor.Tensin@gmail.com>
-- License : MIT
-- Maintainer : Egor.Tensin@gmail.com
-- Stability : experimental
-- Portability : portable
module Prompt
( withPrompt
, withoutPrompt
) where
import Control.Monad (void, when)
import Control.Monad.Trans.Class (lift)
import Control.Monad.Trans.Except (ExceptT)
import Data.Char (toLower)
import System.IO (hFlush, stdout)
prompt :: String -> IO String
prompt msg = do
putStr msg
hFlush stdout
getLine
promptYesNo :: String -> IO Bool
promptYesNo msg = do
response <- map toLower <$> prompt msg
if response `elem` yeses
then return True
else if response `elem` noes
then return False
else promptToContinue
where
yeses = ["y", "yes"]
noes = ["n", "no"]
promptToContinue :: IO Bool
promptToContinue = promptYesNo "Continue? (y/n) "
withPrompt :: String -> ExceptT IOError IO a -> ExceptT IOError IO Bool
withPrompt msg m = do
lift $ do
putStr msg
hFlush stdout
agreed <- lift promptToContinue
when agreed $ void m
return agreed
withoutPrompt :: ExceptT IOError IO a -> ExceptT IOError IO Bool
withoutPrompt m = m >> return True
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