Useful for short-circuiting computations. --- src/Ganeti/Utils/Monad.hs | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/src/Ganeti/Utils/Monad.hs b/src/Ganeti/Utils/Monad.hs index 23df5bd..1753781 100644 --- a/src/Ganeti/Utils/Monad.hs +++ b/src/Ganeti/Utils/Monad.hs @@ -35,6 +35,8 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. module Ganeti.Utils.Monad ( mretryN , retryMaybeN + , anyM + , allM ) where import Control.Monad @@ -49,3 +51,14 @@ mretryN n = msum . flip map [1..n] -- The action signals failure by 'mzero'. retryMaybeN :: (Monad m) => Int -> (Int -> MaybeT m a) -> m (Maybe a) retryMaybeN = (runMaybeT .) . mretryN + + +-- From monad-loops (until we can / want to depend on it): + +-- | Short-circuit 'any' with a monadic predicate. +anyM :: (Monad m) => (a -> m Bool) -> [a] -> m Bool +anyM p = foldM (\v x -> if v then return True else p x) False + +-- | Short-circuit 'all' with a monadic predicate. +allM :: (Monad m) => (a -> m Bool) -> [a] -> m Bool +allM p = foldM (\v x -> if v then p x else return False) True -- 2.1.0.rc2.206.gedb03e5
