croma v0.3.8 Croma.ListMonad

Implementation of Croma.Monad interface for built-in lists.

This empowers the following Haskell-ish syntax for loops using lists:

iex> use Croma
...> Croma.ListMonad.m do
...>   i <- [1, 2, 3]
...>   j <- [10, 20]
...>   pure i + j
...> end
[11, 21, 12, 22, 13, 23]

Summary

Functions

Default implementation of Applicative’s ap operation. Modules that implement Croma.Monad may override this default implementation. Note that the order of arguments is different from the Haskell counterpart, in order to leverage Elixir’s pipe operator |>

Implementation of bind operation of Monad. Alias to Enum.flat_map/2

Default implementation of Functor’s fmap operation. Modules that implement Croma.Monad may override this default implementation. Note that the order of arguments is different from the Haskell counterpart, in order to leverage Elixir’s pipe operator |>

Implementation of pure operation of Monad (or Applicative). Wraps the given value into a list

Converts the given list of monadic (to be precise, applicative) objects into a monadic object that contains a single list. Modules that implement Croma.Monad may override this default implementation

Macros

A macro that provides Hakell-like do-notation

Types

t(a) :: [a]

Functions

ap(ma, mf)

Specs

ap(t(a), t((a -> b))) :: t(b) when a: any, b: any

Default implementation of Applicative’s ap operation. Modules that implement Croma.Monad may override this default implementation. Note that the order of arguments is different from the Haskell counterpart, in order to leverage Elixir’s pipe operator |>.

bind(l, f)

Specs

bind(t(a), (a -> t(b))) :: t(b) when a: any, b: any

Implementation of bind operation of Monad. Alias to Enum.flat_map/2.

map(ma, f)

Specs

map(t(a), (a -> b)) :: t(b) when a: any, b: any

Default implementation of Functor’s fmap operation. Modules that implement Croma.Monad may override this default implementation. Note that the order of arguments is different from the Haskell counterpart, in order to leverage Elixir’s pipe operator |>.

pure(a)

Specs

pure([{:a, a}]) :: t(a) when a: any

Implementation of pure operation of Monad (or Applicative). Wraps the given value into a list.

sequence(list)

Specs

sequence([t(a)]) :: t([a]) when a: any

Converts the given list of monadic (to be precise, applicative) objects into a monadic object that contains a single list. Modules that implement Croma.Monad may override this default implementation.

Examples (using Croma.Result)

iex> Croma.Result.sequence([{:ok, 1}, {:ok, 2}, {:ok, 3}])
{:ok, [1, 2, 3]}

iex> Croma.Result.sequence([{:ok, 1}, {:error, :foo}, {:ok, 3}])
{:error, :foo}

Macros

m(list)

A macro that provides Hakell-like do-notation.

Examples

MonadImpl.m do
  x <- mx
  y <- my
  pure f(x, y)
end

is expanded to

MonadImpl.bind(mx, fn x ->
  MonadImpl.bind(my, fn y ->
    MonadImpl.pure f(x, y)
  end)
end)