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+{-
+ - Copyright 2015 Egor Tensin <Egor.Tensin@gmail.com>
+ - This file is licensed under the terms of the MIT License.
+ - See LICENSE.txt for details.
+-}
+
+module Prompt
+ ( withPrompt
+ , withoutPrompt
+ ) where
+
+import Control.Monad (liftM, void, when)
+import Data.Char (toLower)
+import System.IO (hFlush, stdout)
+
+prompt :: String -> IO String
+prompt banner = do
+ putStr banner
+ hFlush stdout
+ getLine
+
+promptYesNo :: String -> IO Bool
+promptYesNo banner = do
+ response <- liftM (map toLower) $ prompt banner
+ 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 -> IO a -> IO Bool
+withPrompt banner m = do
+ putStr banner
+ hFlush stdout
+ agreed <- promptToContinue
+ when agreed $ void m
+ return agreed
+
+withoutPrompt :: IO a -> IO Bool
+withoutPrompt m = m >> return True