:: f (Maybe a) -> f a -package:extra

Run the supplied Maybe computation repeatedly until it returns a value. Returns that value.

Keep running an operation until it becomes a Just, then return the value inside the Just as the result of the overall loop.

Takes all of the Just values from a sequence of Maybe ts and concatenates them into an unboxed sequence of ts. Since 0.6.2

Keep running an operation until it becomes a Nothing, accumulating the monoid results inside the Justs as the result of the overall loop.

converts MaybeManageHooks to ManageHooks

Evaluate each action in the structure from left to right, and collect the results. For a version that ignores the results see sequenceA_.

Examples

Basic usage: For the first two examples we show sequenceA fully evaluating a a structure and collecting the results.

>>> sequenceA [Just 1, Just 2, Just 3]
Just [1,2,3]

>>> sequenceA [Right 1, Right 2, Right 3]
Right [1,2,3]

The next two example show Nothing and Just will short circuit the resulting structure if present in the input. For more context, check the Traversable instances for Either and Maybe.

>>> sequenceA [Just 1, Just 2, Just 3, Nothing]
Nothing

>>> sequenceA [Right 1, Right 2, Right 3, Left 4]
Left 4

Evaluate each action in the structure from left to right, and collect the results. For a version that ignores the results see sequenceA_.

Evaluate each action in the structure from left to right, and and collect the results. For a version that ignores the results see sequenceA_.

Evaluate each monadic action in the structure from left to right, and collect the results. For a version that ignores the results see sequence_.

Examples

Basic usage: The first two examples are instances where the input and and output of sequence are isomorphic.

>>> sequence $ Right [1,2,3,4]
[Right 1,Right 2,Right 3,Right 4]

>>> sequence $ [Right 1,Right 2,Right 3,Right 4]
Right [1,2,3,4]

The following examples demonstrate short circuit behavior for sequence.

>>> sequence $ Left [1,2,3,4]
Left [1,2,3,4]

>>> sequence $ [Left 0, Right 1,Right 2,Right 3,Right 4]
Left 0

Evaluate each monadic action in the structure from left to right, and collect the results. For a version that ignores the results see sequence_.

Evaluate each action and collect the results.

Evaluate each action and collect the results

Evaluate every action in the vector from left to right.

Deprecated: Use sequence instead