Witchcraft v1.0.0 Witchcraft.Bifunctor View Source

Similar to Witchcraft.Functor, but able to map two functions over two separate portions of some data structure (some product type).

Especially helpful when you need different hebaviours on different fields.

Type Class

An instance of Witchcraft.Bifunctor must also implement Witchcraft.Functor, and define Witchcraft.Apply.ap/2.

 Functor   [map/2]
    ↓
Bifunctor  [bimap/2]

Link to this section Summary

Functions

The same as bimap/3, but with the functions curried

map separate fuctions over two fields in a product type

The same as map_first, but with a curried function

The same as map_second, but with a curried function

map a function over the first value only

map a function over the second value only

Link to this section Types

Link to this section Functions

Link to this function bilift(data, f, g) View Source
bilift(Witchcraft.Bifunctor.t, (... -> any), (... -> any)) :: Witchcraft.Bifunctor.t

The same as bimap/3, but with the functions curried

Examples

iex> {:ok, 2, "hi"}
...> |> bilift(&*/2, &<>/2)
...> |> bimap(fn f -> f.(9) end, fn g -> g.("?!") end)
{:ok, 18, "hi?!"}
Link to this function bimap(data, f, g) View Source
bimap(Witchcraft.Bifunctor.t, (any -> any), (any -> any)) :: Witchcraft.Bifunctor.t

map separate fuctions over two fields in a product type.

The order of fields doesn’t always matter in the map. The first/second function application is determined by the instance. It also does not have to map all fields in a product type.

Diagram

           ┌------------------------------------┐
           ↓                                    |
%Combo{a: 50, b: :ok, c: "hello"} |> bimap(&(&1 * 100), &String.upcase/1)
                             ↑                                 |
                             └---------------------------------┘
#=> %Combo{a: 500, b: :ok, c: "HELLO"}

Examples

iex> {1, "a"} |> bimap(&(&1 * 100), &(&1 <> "!"))
{100, "a!"}

iex> {:msg, 42, "number is below 50"}
...> |> bimap(&(%{subject: &1}), &String.upcase/1)
{:msg, %{subject: 42}, "NUMBER IS BELOW 50"}

The same as map_first, but with a curried function

Examples

iex> {:ok, 2, "hi"}
...> |> lift_first(&*/2)
...> |> map_first(fn f -> f.(9) end)
{:ok, 18, "hi"}

The same as map_second, but with a curried function

Examples

iex> {:ok, 2, "hi"}
...> |> lift_second(&<>/2)
...> |> map_second(fn f -> f.("?!") end)
{:ok, 2, "hi?!"}

map a function over the first value only

Examples

iex> {:ok, 2, "hi"} |> map_first(&(&1 * 100))
{:ok, 200, "hi"}

map a function over the second value only

Examples

iex> {:ok, 2, "hi"} |> map_second(&(&1 <> "!?"))
{:ok, 2, "hi!?"}