Maybe API docs

This is the API documentation for the JFlepp.Maybe library. Please note that the implementations do not show the actual implementation, but rather a reference to look up the behavior.

Type: Maybe

Representation of a maybe value.

Method: Construct

Constructs a some value using the given value.

Parameters

• value: The value of the maybe.

Exceptions

• System.ArgumentNullException: Thrown value is null.

Maybe

public Maybe(T value)
{
	if (value == null) throw new ArgumentNullException(nameof(value));
	(Value, IsSome) = (value, true);
}

Property: IsSome

Gets the type of the Maybe. Returns true if is some, false otherwise.

Property: IsNone

Gets the type of the Maybe. Returns true if is none, false otherwise.

Method: Equals(System.Object)

Indicates whether the current object is equal to another object of the same type.

Parameters

• obj: An object to compare with this object.

Returns: true if the current object is equal to the other parameter; otherwise, false.

Maybe implementation

bool Equals(object obj) => obj is Maybe<T> otherMaybe ? Equals(otherMaybe) : false;

Method: GetHashCode()

Serves as the default hash function.

Returns: A hash code for the current object.

Maybe implementation

int GetHashCode()
{
	unchecked
	{
		return -1584136870 + EqualityComparer<T>.Default.GetHashCode(Value);
	}
}

Method: Equals(Maybe)

Indicates whether the current maybes value is equal to another maybes value.

Parameters

• other: Another maybe to compare with this object.

Returns: true if the current maybe is equal to the other parameter; otherwise, false.

Maybe implementation

bool Equals(Maybe<T> other)
{
	if (IsNone) return other.IsNone;
	if (other.IsNone) return false;

	return Value.Equals(other.Value);
}

Operator: Maybe == Maybe

Checks if two Maybe<T>s are equal.

Parameters

• right: The right Maybe<T> to compare.
• left: The leftMaybe<T> to compare.

Returns: true if objects are equal, false otherwise.

Maybe implementation

bool operator ==(Maybe<T> left, Maybe<T> right) => left.Equals(right);

Operator: Maybe != Maybe

Checks if two Maybe<T>s are not equal.

Parameters

• right: The right Maybe<T> to compare.
• left: The leftMaybe<T> to compare.

Returns: true if objects are not equal, false otherwise.

Maybe implementation

bool operator !=(Maybe<T> left, Maybe<T> right) => !(left == right);

Type: Maybe

Provides functions for creating Maybe<T>s.

Method: None()

Creates a new none instance of Maybe<1>

Returns: A new none instance of Maybe<T>

Method: Some(T value)

Creates a new some instance of Maybe<T>.

Parameters

• value: The value of the Maybe<T>.

Returns: A new some instance of Maybe<T>.

Method: FromObject(T value)

Convert a potentially null value to an option.

Parameters

• value: The input value.

Returns: The result option.

FSharp implementation

let ofObj value = match value with null -> None | _ -> Some value
// val ofObj : value:'a -> 'a option when 'a : null

Maybe implementation

Maybe<T> OfObject<T>(T value) => (value == null) switch
{
	true => Some(value),
	_ => None<T>(),
};

Type: MaybeExtensions

Provides extension methods for working with the Maybe<T> type.

Method: Aggregate<T, TState>(Maybe input, TState state, Func<TState, T, TState> folder)

Applies the supplied function with the supplied initial state and the value of the Maybe<T> if is Some.

Parameters

• input: The input Maybe<T>.
• seed: The initial state.
• func: A function to update the state data when given a value from an option.

Returns: The original state if the Maybe is None, otherwise it returns the updated state with the folder and the Maybe<T> value.

FSharp implementation

let fold{'T,'State} folder (state:'State) (option: option{'T}) = match option with None -> state | Some x -> folder state x
// val fold :
//   folder:('State -> 'T -> 'State) ->
//     state:'State -> option:'T option -> 'State	

Maybe implementation

TState Aggregate<T, TState>(Maybe<T> input, TState state, Func<TState, T, TState> folder) => input.IsNone switch
{
	true => folder(state, input.Value),
	_ => state,
};

Method: All(Maybe input, Predicate predicate)

Evaluates the equivalent of System.Linq.Enumerable.All for a Maybe<T>.

Parameters

• input: The input Maybe<T>.
• predicate: A function that evaluates to a bool when given a value from the Maybe<T>.

Returns: true if the maybe is None, otherwise it returns the result of applying the predicate to the Maybe<T> value.

FSharp implementation

let forall predicate option = match option with None -> true | Some x -> predicate x
// val forall : predicate:('a -> bool) -> option:'a option -> bool

Maybe implementation

bool All<T>(Maybe<T> input, Predicate<T> predicate) => input.IsNone switch
{
	true => predicate(input.Value),
	_ => true,
};

Method: Any(Maybe input, Predicate predicate)

Evaluates the equivalent of System.Linq.Enumerable.Any for a Maybe<T>.

Parameters

• input: The input Maybe<T>.
• predicate: A function that evaluates to a Boolean when given a value from the Maybe<T>.

Returns: Returns false if the Maybe<T> is None, otherwise it returns the result of applying the predicate to the Maybe<T>s value.

FSharp implementation

let exists predicate option = match option with None -> false | Some x -> predicate x
// val exists : predicate:('a -> bool) -> option:'a option -> bool

Maybe implementation

bool Any<T>(Maybe<T> input, Predicate<T> predicate) => input.IsSome switch
{
   true => predicate(input.Value),
   _ => false,
};

Method: Bind<T, TOut>(Maybe input, Func<T, Maybe> binder)

Invokes a function on a Maybe<T> value that itself yields an option.

Parameters

• input: The input Maybe<T>.
• binder: A function that takes the value of type T from a Maybe<T> and transforms it into a Maybe<T> containing a value of type TOut.

Returns: A maybe of the output type of the binder.

FSharp implementation

let bind binder option = match option with None -> None | Some x -> binder x
// val bind : binder:('a -> 'b option) -> option:'a option -> 'b option

Maybe implementation

Maybe<TOut> Bind<T, TOut>(Maybe<T> input, Func<T, Maybe<TOut>> binder) => input.IsSome switch
{
	true => binder(input.Value),
	_ => None{TOut}(),
};

Method: Contains(Maybe input, T value)

Evaluates to true if input is Some and its value is equal to value.

Parameters

• input: The input maybe.
• value: The value to test for equality.

Returns: true if the Maybe<T> is Some and contains a value equal to value, otherwise false.

FSharp implementation

let inline contains value option = match option with None -> false | Some v -> v = value
// let inline contains value option = match option with None -> false | Some v -> v = value

Maybe implementation

bool Contains<T>(Maybe<T> input, T value) => input.IsSome switch
{
	true => input.Value.Equals(value),
	_ => false,
};

Method: Count(Maybe input)

Evaluates the equivalent of System.Linq.Enumerable.Count for a Maybe<T>.

Parameters

• input: The input Maybe<T>.

Returns: A zero if the Maybe<T> is None, a one otherwise.

FSharp implementation

count option = match option with None -> 0 | Some _ -> 1
// val count : option:'a option -> int

Maybe implementation

int Count<T>(Maybe<T> input) => input.IsSome switch
{
	true => 1,
	_ => 0,
};

Method: ForEach(Maybe input, Action action)

Executes a function for a Maybe value if is Some.

Parameters

• input: The input Maybe<T>.
• action: A function to apply to the Maybe value.

FSharp implementation

let iter action option = match option with None -> () | Some x -> action x
// val iter : action:('a -> unit) -> option:'a option -> unit

Maybe implementation

void ForEach<T>(Maybe<T> input, Action<T> action)
{
	if (input.IsSome) action(input.Value);
}

Method: OrElse(Maybe input, T ifNone)

Returns input if it is Some, otherwise returns ifNone.

Parameters

• input: The input option.
• ifNone: The value to use if input is None.

Returns: The input if the maybe is Some, else the alternate value.

FSharp implementation

let orElse ifNone option = match option with None -> ifNone | Some _ -> option
// val orElse : ifNone:'a option -> option:'a option -> 'a option

Maybe implementation

Maybe<T> OrElse<T>(Maybe<T> input, T ifNone) => input.IsSome switch
{
	true => input,
	_ => Maybe.Some(ifNone),
};

Method: OrElse(Maybe input, Func ifNoneThunk)

Returns input if it is Some, otherwise evaluates ifNoneThunk and returns the result.

ifNoneThunk is not evaluated unless input is None.

Parameters

• input: The input option.
• ifNoneThunk: A thunk that provides an alternate option when evaluated.

Returns: The input if the maybe is Some, else the alternate value.

FSharp implementation

let orElseWith ifNoneThunk option = match option with None -> ifNoneThunk () | Some _ -> option
// val orElseWith : ifNoneThunk:(unit -> 'a option) -> option:'a option -> 'a option

Maybe implementation

Maybe<T> OrElse<T>(Maybe<T> input, Func<T> ifNoneThunk) => input.IsSome switch
{
	true => input,
	_ => Maybe.Some(ifNoneThunk()),
};

Method: Select<T, TOut>(Maybe input, Func<T, TOut> mapping)

Transforms a Maybe<T> value by using a specified mapping function.

Parameters

• input: The input Maybe<T>.
• mapping: A function to apply to the Maybe<T> value.

Returns: A Maybe<T> of the result of applying the mapping function, or None if the Maybe<T> is None.

FSharp implementation

let map mapping option = match option with None -> None | Some x -> Some (mapping x)
// val map : mapping:('a -> 'b) -> option:'a option -> 'b option

Maybe implementation

Maybe<TOut> Select<T, TOut>(Maybe<T> input, Func<T, TOut> mapping) => input.IsSome switch
{
	true => Some(mapping(input.Value)),
	_ => None{TOut}()
};

Method: SingleOr(Maybe input, T or)

Gets the value of the maybe if the option is Some, otherwise returns the specified default value.

Parameters

• input: The input maybe.
• or: The specified default value.

Returns: The option if the option is Some, else the default value.

FSharp implementation

let defaultValue value option = match option with None -> value | Some v -> v
// val defaultValue : value:'a -> option:'a option -> 'a

Maybe implementation

T SingleOr<T>(Maybe<T> input, T or) => input.IsSome switch
{
	true => input.Value,
	_ => or,
};

Method: SingleOr(Maybe input, Func or)

Gets the value of the option if the maybe is Some, otherwise evaluates or and returns the result.

Parameters

• input: The input maybe.
• or: A thunk that provides a default value when evaluated.

Returns: The maybe if the maybe is Some, else the result of evaluating or.

FSharp implementation

let defaultWith defThunk option = match option with None -> defThunk () | Some v -> v
// val defaultWith : defThunk:(unit -> 'a) -> option:'a option -> 'a

Maybe implementation

T SingleOr<T>(Maybe<T> input, Func<T> or) => input.IsSome switch
{
	true => input.Value,
	_ => or.ThrowIfNull(nameof(or))(),
};

Method: ToArray(Maybe input)

Convert the Maybe<T> to an array of length 0 or 1.

Parameters

• input: The input Maybe<T>.

Returns: The result array.

FSharp implementation

let toArray option = match option with  None -> [| |] | Some x -> [| x |]
// val toArray : option:'a option -> 'a []

Maybe implementation

T[] ToArray<T>(Maybe<T> input) => input.IsSome switch
{
	true => new[] { input.Value },
	_ => Array.Empty{T}(),
};

Method: ToList(Maybe input)

Convert the Maybe<T> to a list of length 0 or 1.

Parameters

• input: The input Maybe<T>.

Returns: The result list.

FSharp implementation

let toList option = match option with  None -> [ ] | Some x -> [ x ]
// let toList option = match option with  None -> [ ] | Some x -> [ x ]

Maybe implementation

List<T> ToList<T>(Maybe<T> input) => input.IsSome switch
{
	true => new List{T} { input.Value },
	_ => new List{T}(),
};

Method: ToObject(Maybe input)

Convert an Maybe<T> to a potentially null value.

Parameters

• input The input value.

Returns: The result value, which is null if the input was None.

FSharp implementation

let toObj value = match value with None -> null | Some x -> x
// val toObj : value:'a option -> 'a when 'a : null

Maybe implementation

object ToObject<T>(Maybe<T> input) => input.IsSome switch
{
	true => input.Value,
	_ => null,
}; 

Method: Where(Maybe input, Predicate predicate)

Invokes a function on a Maybe<T> that itself yields an option.

Parameters

• input: The input Maybe<T>.
• predicate A function that evaluates whether the value contained in the Maybe<T> should remain, or be filtered out.

Returns: The input if the predicate evaluates to true; otherwise, None.

FSharp implementation

let filter predicate option = match option with None -> None | Some x -> if predicate x then Some x else None
// val filter : predicate:('a -> bool) -> option:'a option -> 'a option

Maybe implementation

Maybe<T> Where<T>(Maybe<T> input, Predicate<T> predicate) => input.IsSome switch
{
	true => predicate(input.Value) ? input : None{T}(),
	_ => None{T}(),
};

Type: MaybeStructExtensions

Provides extensions for struct Maybes.

Method: ToNullable(Maybe input)

Convert the Maybe<T> to a Nullable value.

Returns: null if the Maybe<T> is None, the value otherwise.

FSharp implementation

let toNullable option = match option with None -> System.Nullable() | Some v -> System.Nullable(v)
// val toNullable :
//  option:'a option -> System.Nullable{'a}
//      when 'a : (new : unit -> 'a) and 'a : struct and 'a :> System.ValueType

Maybe implementation

T? ToNullable<T>(Maybe<T> input) where T : struct => input.IsSome switch
{
	true => input.Value,
	_ => null,
};

Type: MaybeReferenceExtensions

Provides extensions for reference Maybes.

Method: ToNullable(Maybe input)

Convert the Maybe<T> to a Nullable value.

Returns: null if the Maybe<T> is None, the value otherwise.

FSharp implementation

let toNullable option = match option with None -> System.Nullable() | Some v -> System.Nullable(v)
// val toNullable :
//  option:'a option -> System.Nullable{'a}
//      when 'a : (new : unit -> 'a) and 'a : struct and 'a :> System.ValueType

Maybe implementation

T ToNullable<T>(Maybe<T> input) where T : class => input.IsSome switch
{
	true => input.Value,
	_ => null,
};

Type: Unsafe.MaybeExtensions

Provides unsafe extensions for Maybe<T>s.

Method: GetValue(Maybe input)

Gets the value of the maybe if is Some.

Parameters

• input: The Maybe<T> to get the value from.

Returns: The value of the Maybe<T> if is Some.

Exceptions

• System.NullReferenceException: If the maybe is None.

FSharp implementation

let get option = match option with None -> invalidArg "option" (SR.GetString(SR.optionValueWasNone)) | Some x -> x
// val get: option:'T option -> 'T

Maybe implementation

T GetValue<T>(Maybe<T> input) => input.IsSome switch
{
	true => input.Value,
	_ => throw new NullReferenceException(),
};