Quark.Compose (Quark v2.3.2) View Source

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

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

g <|> f

Infix compositon operator

f <~> g

Infix "forward" compositon operator

compose(funcs)

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

compose(g, f)

Function composition

compose_forward(funcs)

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

compose_forward(f, g)

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

Link to this section Functions

g <|> f

Specs

(... -> any()) <|> (... -> any()) :: (... -> any())

Infix compositon operator

Examples

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

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

f <~> g

Specs

(... -> any()) <~> (... -> any()) :: (... -> any())

Infix "forward" compositon operator

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)

Specs

compose([(... -> any())]) :: (... -> any())

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

Examples

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

compose(g, f)

Specs

compose((... -> any()), (... -> any())) :: any()

Function composition

Examples

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

compose_forward(funcs)

Specs

compose_forward([(... -> any())]) :: (... -> any())

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

Examples

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

compose_forward(f, g)

Specs

compose_forward((... -> any()), (... -> any())) :: (... -> any())

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

Examples

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