diff options
Diffstat (limited to 'libraries/base/Data/Foldable.hs')
| -rw-r--r-- | libraries/base/Data/Foldable.hs | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/libraries/base/Data/Foldable.hs b/libraries/base/Data/Foldable.hs index e2d792a1f2..084d846be2 100644 --- a/libraries/base/Data/Foldable.hs +++ b/libraries/base/Data/Foldable.hs @@ -1175,7 +1175,7 @@ sequence_ = foldr c (return ()) where c m k = m >> k {-# INLINE c #-} --- | The sum of a collection of actions, generalizing 'concat'. +-- | The sum of a collection of actions using '(<|>)', generalizing 'concat'. -- -- 'asum' is just like 'msum', but generalised to 'Alternative'. -- @@ -1189,10 +1189,16 @@ asum :: (Foldable t, Alternative f) => t (f a) -> f a {-# INLINE asum #-} asum = foldr (<|>) empty --- | The sum of a collection of actions, generalizing 'concat'. +-- | The sum of a collection of actions using '(<|>)', generalizing 'concat'. -- -- 'msum' is just like 'asum', but specialised to 'MonadPlus'. -- +-- ==== __Examples__ +-- +-- Basic usage, using the 'MonadPlus' instance for 'Maybe': +-- +-- >>> msum [Just "Hello", Nothing, Just "World"] +-- Just "Hello" msum :: (Foldable t, MonadPlus m) => t (m a) -> m a {-# INLINE msum #-} msum = asum |