monad.hpp File Reference

#include <tl_expected/expected.hpp>
#include <optional>

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Functions
template<typename T , typename Fn >
constexpr auto	rsl::mbind (std::optional< T > const &opt, Fn fn) -> std::invoke_result_t< Fn, T >
	Monad optional bind.
template<typename T , typename E , typename Fn >
constexpr auto	rsl::mbind (tl::expected< T, E > const &exp, Fn fn) -> std::invoke_result_t< Fn, T >
	Monad tl::expected<T,E>
template<typename Fn >
auto	rsl::mtry (Fn fn) -> tl::expected< std::invoke_result_t< Fn >, std::exception_ptr > try
	Monadic try, used to lift a function that throws an exception into one that returns an tl::expected<T, std::exception_ptr>
	rsl::catch (...)
template<typename Fn , typename G >
constexpr auto	rsl::mcompose (Fn fn, G g)
	Monadic compose two monad functions.
template<typename T , typename G , typename... Ts>
constexpr auto	rsl::mcompose (T t, G g, Ts... vars)
	Variadic mcompose.
template<typename T , typename E >
constexpr auto	rsl::has_error (tl::expected< T, E > const &exp)
	Test if expected type is Error.
template<typename T , typename E >
constexpr auto	rsl::has_value (tl::expected< T, E > const &exp)
	Test if expected type is Value.
template<typename E , typename... Args>
constexpr auto	rsl::maybe_error (tl::expected< Args, E >... args)
	Tests if any of the expected args passed in has an error.
template<typename T , typename Fn , typename = std::enable_if_t<rsl::is_optional<T>>, typename = std::enable_if_t<std::is_invocable_v< Fn, typename std::remove_cv_t<std::remove_reference_t<T>>::value_type>>>
constexpr auto	operator| (T &&opt, Fn &&fn)
	Overload of the | operator as bind.
template<typename T , typename E , typename Fn >
constexpr auto	operator| (tl::expected< T, E > const &exp, Fn fn)
	Overload of the | operator as bind.
template<typename T , typename Fn , typename = std::enable_if_t<!rsl::is_optional<T>>>
constexpr auto	operator| (T &&val, Fn &&fn) -> typename std::enable_if_t< std::is_invocable_v< Fn, T >, std::invoke_result_t< Fn, T > >
	Overload of the | operator for unary functions.

Variables
template<typename >
constexpr bool	rsl::is_optional_impl = false
template<typename T >
constexpr bool	rsl::is_optional = is_optional_impl<std::remove_cv_t<std::remove_reference_t<T>>>

Function Documentation

has_error()

template<typename T , typename E >

constexpr auto rsl::has_error ( tl::expected< T, E > const &  exp )

constexpr

Test if expected type is Error.

Parameters

exp	Input tl::expected<T,E> value

Returns

True if expected paraemter is Error

has_value()

template<typename T , typename E >

constexpr auto rsl::has_value ( tl::expected< T, E > const &  exp )

constexpr

Test if expected type is Value.

Parameters

exp	Input tl::expected<T,E> value

Returns

True if expected paraemter is Value

maybe_error()

template<typename E , typename... Args>

constexpr auto rsl::maybe_error ( tl::expected< Args, E >...  args )

constexpr

Tests if any of the expected args passed in has an error.

Parameters

args	tl::expected<T, E> parameter pack

Template Parameters

E	The error type
Args	The value types for the tl::expected<T, E> args

Returns

The first error found or nothing

mbind() [1/2]

template<typename T , typename Fn >

constexpr auto rsl::mbind ( std::optional< T > const &  opt, Fn  fn  ) -> std::invoke_result_t<Fn, T>

constexpr

Monad optional bind.

Parameters

opt	Input optional
fn	Function, must return a optional

Template Parameters

T	Input type
Fn	Function

Returns

Return type of fn

mbind() [2/2]

template<typename T , typename E , typename Fn >

constexpr auto rsl::mbind ( tl::expected< T, E > const &  exp, Fn  fn  ) -> std::invoke_result_t<Fn, T>

constexpr

Monad tl::expected<T,E>

Parameters

exp	tl::expected<T,E> input
fn	Function to apply

Template Parameters

T	Type for the input expected
E	Error type
Fn	Function

Returns

Return type of the function

mcompose() [1/2]

template<typename Fn , typename G >

constexpr auto rsl::mcompose ( Fn  fn, G  g  )

constexpr

Monadic compose two monad functions.

Parameters

fn	First function
g	Second function

Template Parameters

Fn	Type of the first function
G	Type of the second function

Returns

A functional composition of two monad functions

mcompose() [2/2]

template<typename T , typename G , typename... Ts>

constexpr auto rsl::mcompose ( T  t, G  g, Ts...  vars  )

constexpr

Variadic mcompose.

Parameters

t	First function
g	Second function
vars	Rest of the functions

Template Parameters

T	Type of the first function
G	Type of the second function
Ts	Types of the rest of the functions

Returns

A functional composition of variadic monad functions

mtry()

template<typename Fn >

auto rsl::mtry

(

Fn

fn

)

-> tl::expected<std::invoke_result_t<Fn>, std::exception_ptr> try

Monadic try, used to lift a function that throws an exception into one that returns an tl::expected<T, std::exception_ptr>

Parameters

fn	Function to call

Template Parameters

Fn	Function type

Returns

Return value of the function

operator|() [1/3]

template<typename T , typename Fn , typename = std::enable_if_t<rsl::is_optional<T>>, typename = std::enable_if_t<std::is_invocable_v< Fn, typename std::remove_cv_t<std::remove_reference_t<T>>::value_type>>>

constexpr auto operator| ( T &&  opt, Fn &&  fn  )

constexpr

Overload of the | operator as bind.

Parameters

opt	Input optional
fn	Function

Template Parameters

T	Input type
Fn	Function

Returns

Return type of f

operator|() [2/3]

template<typename T , typename Fn , typename = std::enable_if_t<!rsl::is_optional<T>>>

constexpr auto operator| ( T &&  val, Fn &&  fn  ) -> typename std::enable_if_t<std::is_invocable_v<Fn, T>, std::invoke_result_t<Fn, T>>

constexpr

Overload of the | operator for unary functions.

Parameters

val	Input value
fn	Function to apply on val

Template Parameters

T	Type for the input
Fn	Function

Returns

Return the result of invoking the function on val

operator|() [3/3]

template<typename T , typename E , typename Fn >

constexpr auto operator| ( tl::expected< T, E > const &  exp, Fn  fn  )

constexpr

Overload of the | operator as bind.

Parameters

exp	Input tl::expected<T,E> value
fn	Function to apply

Template Parameters

T	Type for the input expected
E	Error type
Fn	Function

Returns

Return type of fn