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Diffstat (limited to 'testsuite/tests/deSugar/should_run/dsrun010.hs')
-rw-r--r-- | testsuite/tests/deSugar/should_run/dsrun010.hs | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/testsuite/tests/deSugar/should_run/dsrun010.hs b/testsuite/tests/deSugar/should_run/dsrun010.hs new file mode 100644 index 0000000000..99a9297f8b --- /dev/null +++ b/testsuite/tests/deSugar/should_run/dsrun010.hs @@ -0,0 +1,22 @@ +-- Check that pattern match failure in do-notation +-- is reflected by calling the monadic 'fail', not by a +-- runtime exception + +import Control.Monad +import Data.Maybe + +test :: (MonadPlus m) => [a] -> m Bool +test xs + = do + (_:_) <- return xs + -- Should fail here + return True + `mplus` + -- Failure in LH arg should trigger RH arg + do + return False + +main :: IO () +main + = do let x = fromJust (test []) + putStrLn (show x) |