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sourcecode:
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module CPM.Helpers ( stripSpaces, stripEnclosing, askYesNo ) where
import Data.Char ( isSpace, toLower )
import Data.List ( init, isPrefixOf, last )
import System.IO ( hFlush, stdout )
--- Strips leading and tailing spaces:
stripSpaces :: String -> String
stripSpaces = reverse . dropWhile isSpace . reverse . dropWhile isSpace
--- Strips a leading and tailing character if they are present.
stripEnclosing :: Char -> Char -> String -> String
stripEnclosing lc tc s = case s of
c1:cs@(_:_) | c1 == lc && last cs == tc -> init cs
_ -> s
-- Ask a question and return the answer which must be empty, `yes`, or `no`.
askYesNo :: String -> IO String
askYesNo question = do
putStr question
hFlush stdout
answer <- fmap (map toLower) getLine
if null answer
then return answer
else if answer `isPrefixOf` "yes"
then return "yes"
else if answer `isPrefixOf` "no"
then return "no"
else askYesNo question -- again
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