module Utils where import Control.Exception (ErrorCall, catch) import Control.Monad import Control.Monad.Trans.Control import System.IO.Silently import Data.Tuple (swap) import Test.HUnit hiding (State) -- | capture stdout -- [[https://stackoverflow.com/a/11128420][source]] catchOutput :: IO a -> IO (a, String) catchOutput f = swap `fmap` capture f showLn :: Show a => a -> String showLn x = unlines $ [show x] showLines :: Show a => [a] -> String showLines xs = unlines $ map show xs withError :: a -> ErrorCall -> a withError a _ = a assertUndefined :: a -> Assertion assertUndefined a = catch (seq a $ assertFailure "") (withError $ return ()) assertNoUndefined :: a -> Assertion assertNoUndefined a = catch (seq a $ return ()) (withError $ assertFailure "") allEqual :: Eq a => [a] -> Bool allEqual = all (uncurry (==)) . pairs where pairs l = zip l $ tail l safeLast :: [a] -> Maybe a safeLast [] = Nothing safeLast l = Just $ last l add :: Monad m => m Int -> m Int -> m Int add = liftM2 (+) doThing :: MonadBaseControl b m => m a -> m a doThing = liftBaseOp_ go where go :: Monad m => m a -> m a go a = return () >> a