WriterT

 
public final class WriterT<F, W, A> : WriterTOf<F, W, A>

WriterT transformer represents operations that accumulate values through a computation or effect, without reading them.

  • Safe downcast.

    Declaration

    Swift

    public static func fix(_ fa: WriterTOf<F, W, A>) -> WriterT<F, W, A>

    Parameters

    fa

    Value in the higher-kind form.

    Return Value

    Value cast to WriterT.

  • Initializes a WriterT.

    Declaration

    Swift

    public init(_ value: Kind<F, (W, A)>)

    Parameters

    value

    A pair of accumulator and value wrapped in an effect.

  • Provides the values wrapped in this WriterT

    Declaration

    Swift

    public var runT: Kind<F, (W, A)> { get }

Functions for Writer

  • Initializes a Writer.

    Declaration

    Swift

    public convenience init(_ value: (W, A))

    Parameters

    value

    A pair of accumulator and value.

  • Initializes a Writer.

    Declaration

    Swift

    public convenience init(_ w: W, _ a: A)

    Parameters

    w

    The accumulator initial value.
    a

    The initial value.

  • Provides the values wrapped in this Writer

    Declaration

    Swift

    public var run: (W, A) { get }

  • The first element of the pair.

    Declaration

    Swift

    public var first: W { get }

  • The second element of the pair.

    Declaration

    Swift

    public var second: A { get }

Functions for WriterT when the effect has an instance of Functor

  • Adds an accumulated value to an effect.

    Declaration

    Swift

    public static func putT(_ fa: Kind<F, A>, _ w: W) -> WriterT<F, W, A>

    Parameters

    fa

    A value wrapped in an effect.
    w

    A value for the accumulator.

    Return Value

    A WriterT where the effect wraps the original value with the accumulator.

  • Obtains an effect with the result value.

    Declaration

    Swift

    public func content() -> Kind<F, A>

    Return Value

    Effect with the result value.

  • Obtains an effect with the accumulator value.

    Declaration

    Swift

    public func written() -> Kind<F, W>

    Return Value

    Effect with the accumulator value.

Functions for WriterT when the effect has an instance of Functor and the accumulator type has an instance of Monoid

  • Lifts an effect to a WriterT using the empty value of the Monoid as the accumulator.

    Declaration

    Swift

    public static func valueT(_ fa: Kind<F, A>) -> WriterT<F, W, A>

    Parameters

    fa

    An effect.

    Return Value

    A WriterT where the effect wraps the original value with an empty accumulator.

Functions for WriterT when the effect has an instance of Applicative

  • Creates a WriterT from values for the result and accumulator.

    Declaration

    Swift

    public static func both(_ w: W, _ a: A) -> WriterT<F, W, A>

    Parameters

    w

    Initial value for the accumulator.
    a

    Initial value for the result.

    Return Value

    A WriterT wrapping the provided values in an effect.

  • Creates a WriterT from a tuple.

    Declaration

    Swift

    public static func fromTuple(_ z: (W, A)) -> WriterT<F, W, A>

    Parameters

    z

    A tuple where the first component is used for the accumulator and the second for the result value.

    Return Value

    A WriterT wrapping the provided values in an effect.

  • Creates a WriterT from values for the result and accumulator.

    Declaration

    Swift

    public static func put(_ a: A, _ w: W) -> WriterT<F, W, A>

    Parameters

    a

    Initial value for the result.
    w

    Initial value for the accumulator.

    Return Value

    A WriterT wrapping the provided values in an effect.

  • Lifts an effect using the accumulator value of this WriterT.

    Declaration

    Swift

    public func liftF<B>(_ fb: Kind<F, B>) -> WriterT<F, W, B>

    Parameters

    fb

    Effect to be lifted.

    Return Value

    A WriterT wrapping the value contained in the effect parameter and using the accumulator of this WriterT.

Functions for WriterT when the effect has an instance of Applicative and the accumulator type has an instance of Monoid

  • Creates a WriterT from an initial value for the result.

    Declaration

    Swift

    public static func value(_ a: A) -> WriterT<F, W, A>

    Parameters

    a

    Initial value for the result.

    Return Value

    A WriterT wrapping the provided value and using the empty value of the Monoid for the accumulator.

Functions for WriterT when the effect has an instance of Monad

  • Transforms the accumulator and result values using a provided function.

    Declaration

    Swift

    public func transform<B, U>(_ f: @escaping ((W, A)) -> (U, B)) -> WriterT<F, U, B>

    Parameters

    f

    Transforming function.

    Return Value

    A WriterT where the original values have been transformed using the provided function.

  • Transforms the wrapped value using a provided function.

    Declaration

    Swift

    public func transformT<B, U>(_ f: @escaping (Kind<F, (W, A)>) -> Kind<F, (U, B)>) -> WriterT<F, U, B>

    Parameters

    f

    Transforming function.

    Return Value

    A WriterT where the original values have been transformed using the provided function.

  • Transforms the accumulator using the provided function.

    Declaration

    Swift

    public func mapAcc<U>(_ f: @escaping (W) -> U) -> WriterT<F, U, A>

    Parameters

    f

    Transforming function.

    Return Value

    A WriterT with the same result as the original one, and the transformed accumulator.

  • Transforms the accumulator and result values using two functions.

    Declaration

    Swift

    public func bimap<B, U>(_ g: @escaping (W) -> U, _ f: @escaping (A) -> B) -> WriterT<F, U, B>

    Parameters

    g

    Transforming function for the accumulator.
    f

    Transforming function for the result.

    Return Value

    A WriterT where the original values have been transformed using the provided functions.

  • Flatmaps the provided function to the nested tuple.

    Declaration

    Swift

    public func subflatMap<B>(_ f: @escaping (A) -> (W, B)) -> WriterT<F, W, B>

    Parameters

    f

    Function for the flatmap operation.

    Return Value

    Result of flatmapping the provided function to the nested values, wrapped in the effect.

  • Swaps the result and accumulator values.

    Declaration

    Swift

    public func swap() -> WriterT<F, A, W>

    Return Value

    A WriterT where the accumulator is the original result value and vice versa.

  • Runs this effect and pairs the result with the accumulator for a new result.

    Declaration

    Swift

    public func listen() -> WriterTOf<F, W, (W, A)>

    Return Value

    A WriterT where the result is paired with the accumulator.

Functions for WriterT when the effect has an instance of Monad and the accumulator type has an instance of Monoid

  • Flatmaps a function that produces an effect and lifts it back to WriterT.

    Declaration

    Swift

    public func semiflatMap<B>(_ f: @escaping (A) -> Kind<F, B>) -> WriterT<F, W, B>

    Parameters

    f

    A function producing an effect.

    Return Value

    Result of flatmapping and lifting the function on this value.

  • Resets the accumulator to the empty value of the Monoid.

    Declaration

    Swift

    public func reset() -> WriterT<F, W, A>

    Return Value

    A WriterT value with an empty accumulator and the same result value.