Hike (hike v0.1.0)

Hike is a library that provides elevated data types, namely Option, Either, and MayFail, in the Elixir programming language. These elevated data types offer additional functionality and safety compared to the basic data types provided by Elixir.

Option: The Hike.Option type represents a value that may or may not be present. It allows you to handle cases where a value might be absent without resorting to using nil or throwing exceptions. The Option type provides functions like bind, map, and match to perform operations on the encapsulated value while handling the absence of the value gracefully.

Either: The Hike.Either type represents a value that can be one of two possibilities: left or right. It is commonly used to handle cases where a computation can result in either a successful outcome or a specific error. The Either type provides functions like bind_left, bind_right, map_left, map_right, and match to perform operations on the encapsulated values based on their respective sides.

MayFail: The Hike.MayFail type combines the benefits of both Option and Either. It represents a value that can either succeed or fail, similar to Either, but allows for more fine-grained error handling and composition. It provides functions like bind_success, bind_failure, map_success, and map_failure to work with the success and failure cases. The primary purpose of Hike is to enhance

  • expressiveness,
  • safety,
  • and predictability in code by providing these elevated data types.

They enable developers to handle different scenarios and errors in a more structured and controlled manner, reducing the reliance on exceptions and mutable state.

The functional programming paradigm is promoted by focusing on

  • immutability,
  • pure functions,
  • and composition, which leads to more maintainable and robust code.

By using Hike, developers can write code that is easier to reason about, handle potential errors explicitly, and compose operations on elevated data types in a more concise and declarative manner.

It defines

  • a struct Hike.Option with a single field value which can either be nil or any other value of type <T>.

  • a struct Hike.Either that represents an "either/or" value. It can contain either a left value or a right value, but not both

  • a struct Hike.MayFailthat represents an "either/or" value. It can contain either a Failure value or a Success value, but not both.

This implementation provides shorthand functions to work with Optional data, including mapping, filtering, applying and many more functions to the value inside the Optional data.

purpose of this is to provide shorthand functions at Hike module itself.

## Example

iex> Hike.option(42)
%Hike.Option{value: 42}

iex> Hike.either(42)
%Hike.Either{l_value: nil, r_value: 42, is_left?: false}

iex> Hike.either({:ok, 42})
%Hike.Either{l_value: nil, r_value: 42, is_left?: false}

iex> Hike.either({:error, :ERROR_MSG})
%Hike.Either{l_value: :ERROR_MSG, r_value: nil, is_left?: true}

iex> Hike.mayfail(9)
%Hike.MayFail{failure: nil, success: 9, is_success?: true}

iex> Hike.mayfail({:ok, 9})
%Hike.MayFail{failure: nil, success: 9, is_success?: true}

iex> Hike.mayfail({:error, "ERR_MSG"})
%Hike.MayFail{failure: "ERR_MSG", success: nil, is_success?: false}

iex> option = Hike.option(42)
...> Hike.map(option, &(&1 * 2))
%Hike.Option{value: 84}

iex> eth = Hike.either(42)
...> Hike.map_left(eth, &(&1 * 2))
%Hike.Either{l_value: nil, r_value: 42, is_left?: false}
iex> eth = Hike.either(42)
...> Hike.map_right(eth, &(&1 * 2))
%Hike.Either{l_value: nil, r_value: 84, is_left?: false}

iex> may_fail = Hike.mayfail(9)
...> Hike.map_success(may_fail, &(&1 * 2))
%Hike.MayFail{failure: nil, success: 18, is_success?: true}


iex> defmodule HikeTest do
...>   alias Hike
...>   def divide(x, y), do: x / y
...>     def test_divide(x, y) do
...>      Hike.try(&divide/2, x, y)
...>    end
...> end

...> HikeTest.test_divide(4, 2) |> Hike.map_success(fn x -> x + 1 end)
...> HikeTest.test_divide(4, 0) |> Hike.map_success(fn x -> x + 1 end)
%Hike.MayFail{failure: nil, success: 3.0, is_success?: true}
%Hike.MayFail{
failure: "bad argument in arithmetic expression",
success: nil,
is_success?: false
}

Application didn't crash but successfully return error.

like this example all other function can be used from Hike module itself.

Link to this section Summary

Types

t()

generic input type <T>.

generic input type <TArg1>.

generic input type <TArg2>.

generic input type <TArg3>.

generic input type <TArg4>.

generic return type <TR>.

Functions

wraps a function call if function runs successfully will return MayFail in Success state otherwise return MayFail in Failure state.

wraps a function with arity 1 call if function runs successfully will return MayFail in Success state otherwise return MayFail in Failure state.

wraps a function with arity 2 call if function runs successfully will return MayFail in Success state otherwise return MayFail in Failure state.

wraps a function with arity 3 call if function runs successfully will return MayFail in Success state otherwise return MayFail in Failure state.

wraps a function with arity 4 call if function runs successfully will return MayFail in Success state otherwise return MayFail in Failure state.

Link to this section Types

@type exception() :: :error
@type t() :: any()

generic input type <T>.

@type tArg1() :: any()

generic input type <TArg1>.

@type tArg2() :: any()

generic input type <TArg2>.

@type tArg3() :: any()

generic input type <TArg3>.

@type tArg4() :: any()

generic input type <TArg4>.

@type tr() :: any()

generic return type <TR>.

Link to this section Functions

Link to this function

apply(opt, func)

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apply_failure(mayfail, func)

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apply_left(eth, func)

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apply_right(eth, func)

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apply_success(mayfail, func)

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bind(opt, func)

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bind_failure(mayfail, func)

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bind_left(eth, func)

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bind_right(eth, func)

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bind_success(mayfail, func)

@spec either({:ok, t()}) :: Hike.Either.either_right(t())
@spec either({:error, t()}) :: Hike.Either.either_left(t())
@spec either(t()) :: Hike.Either.either_right(t())
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filter(opt, func)

@spec left(t()) :: Hike.Either.either_left(t())
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map_failure(mayfail, func)

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map_left(eth, func)

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map_right(eth, func)

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map_success(mayfail, func)

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match(opt, some_func, none_func)

@spec mayfail({:ok, t()}) :: Hike.MayFail.mayfail_success(t())
@spec mayfail({:error, exception()}) :: Hike.MayFail.mayfail_failure(exception())
@spec mayfail(t()) :: Hike.MayFail.mayfail_success(t())
@spec option() :: Hike.Option.option()
@spec option({:ok, t()}) :: Hike.Option.option(t())
@spec option({:error, exception()}) :: Hike.Option.option()
@spec option(t()) :: Hike.Option.option() | Hike.Option.option(t())
@spec right(t()) :: Hike.Either.either_right(t())
@spec success(t()) :: Hike.MayFail.mayfail_success(t())
@spec try((() -> tr() | exception())) :: Hike.MayFail.mayfail()

wraps a function call if function runs successfully will return MayFail in Success state otherwise return MayFail in Failure state.

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try(func, arg1)

@spec try((tArg1() -> tr() | exception()), tArg1()) :: Hike.MayFail.mayfail()

wraps a function with arity 1 call if function runs successfully will return MayFail in Success state otherwise return MayFail in Failure state.

example

Example

iex>  add1 = fn (x) -> x + 1 end
iex>  Hike.try(add1, 5) |> Hike.MayFail.map_success(fn  x -> x end )
%Hike.MayFail{failure: nil, success: 6, is_success?: true}
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try(func, arg1, arg2)

@spec try((tArg1(), tArg2() -> tr() | exception()), tArg1(), tArg2()) ::
  Hike.MayFail.mayfail()

wraps a function with arity 2 call if function runs successfully will return MayFail in Success state otherwise return MayFail in Failure state.

example

Example

iex>  divide = fn (x, y) -> x / y end
iex>  Hike.try(divide, 5, 0) |>
...>  Hike.MayFail.map_success(fn  x -> {:ok, x + 1} end ) |>
...>  Hike.MayFail.map_failure(fn x -> String.upcase(x) end)

  %Hike.MayFail{
    failure: "BAD ARGUMENT IN ARITHMETIC EXPRESSION",
    success: nil,
    is_success?: false
  }
Link to this function

try(func, arg1, arg2, arg3)

@spec try(
  (tArg1(), tArg2(), tArg3() -> tr() | exception()),
  tArg1(),
  tArg2(),
  tArg3()
) ::
  Hike.MayFail.mayfail()

wraps a function with arity 3 call if function runs successfully will return MayFail in Success state otherwise return MayFail in Failure state.

Link to this function

try(func, arg1, arg2, arg3, arg4)

@spec try(
  (tArg1(), tArg2(), tArg3(), tArg4() -> tr() | exception()),
  tArg1(),
  tArg2(),
  tArg3(),
  tArg4()
) :: Hike.MayFail.mayfail()

wraps a function with arity 4 call if function runs successfully will return MayFail in Success state otherwise return MayFail in Failure state.