concat package:protolude

concat :: Foldable t => t [a] -> [a]

The concatenation of all the elements of a container of lists.

Basic usage:

>>> concat (Just [1, 2, 3])
[1,2,3]

>>> concat (Left 42)
[]

>>> concat [[1, 2, 3], [4, 5], [6], []]
[1,2,3,4,5,6]

Map a function over all the elements of a container and concatenate the resulting lists.

Basic usage:

>>> concatMap (take 3) [[1..], [10..], [100..], [1000..]]
[1,2,3,10,11,12,100,101,102,1000,1001,1002]

>>> concatMap (take 3) (Just [1..])
[1,2,3]

Reduce a non-empty list with <> The default definition should be sufficient, but this can be overridden for efficiency.

For the following examples, we will assume that we have:

>>> import Data.List.NonEmpty (NonEmpty (..))

>>> sconcat $ "Hello" :| [" ", "Haskell", "!"]
"Hello Haskell!"

>>> sconcat $ Just [1, 2, 3] :| [Nothing, Just [4, 5, 6]]
Just [1,2,3,4,5,6]

>>> sconcat $ Left 1 :| [Right 2, Left 3, Right 4]
Right 2