# View Source Quark.Compose(Quark v2.3.3-doma)

Function composition is taking two functions, and joining them together to create a new function. For example:

## examples Examples

``````iex> sum_plus_one = compose([&(&1 + 1), &Enum.sum/1])
...> sum_plus_one.([1,2,3])
7``````

In this case, we have joined `Enum.sum` with a function that adds one, to create a new function that takes a list, sums it, and adds one.

Note that composition normally applies from right to left, though `Quark` provides the opposite in the form of `*_forward` functions.

# Link to this section Summary

## Functions

Infix "forward" compositon operator

Function composition, from the tail of the list to the head

Function composition

Compose functions, from the head of the list of functions.

Function composition, from the head to tail (left-to-right)

# f <~> g

View Source
`@spec (... -> any()) <~> (... -> any()) :: (... -> any())`

Infix "forward" compositon operator

## examples Examples

``````iex> sum_plus_one = (&Enum.sum/1) <~> fn x -> x + 1 end
...> sum_plus_one.([1, 2, 3])
7

iex> x200 = (&(&1 * 2)) <~> (&(&1 * 10)) <~> (&(&1 * 10))
...> x200.(5)
1000

iex> add_one  = &(&1 + 1)
...> piped    = [1, 2, 3] |> Enum.sum() |> add_one.()
...> composed = [1, 2, 3] |> ((&Enum.sum/1) <~> add_one).()
...> piped == composed
true``````

# compose(funcs)

View Source
`@spec compose([(... -> any())]) :: (... -> any())`

Function composition, from the tail of the list to the head

## examples Examples

``````iex> sum_plus_one = compose([&(&1 + 1), &Enum.sum/1])
...> [1,2,3] |> sum_plus_one.()
7``````

# compose(g, f)

View Source
`@spec compose((... -> any()), (... -> any())) :: any()`

Function composition

## examples Examples

``````iex> sum_plus_one = compose(&(&1 + 1), &Enum.sum/1)
...> [1, 2, 3] |> sum_plus_one.()
7``````

# compose_forward(funcs)

View Source
`@spec compose_forward([(... -> any())]) :: (... -> any())`

Compose functions, from the head of the list of functions.

## examples Examples

``````iex> sum_plus_one = compose_forward([&Enum.sum/1, &(&1 + 1)])
...> sum_plus_one.([1, 2, 3])
7``````
`@spec compose_forward((... -> any()), (... -> any())) :: (... -> any())`
``````iex> sum_plus_one = compose_forward(&Enum.sum/1, &(&1 + 1))