PLens

 
public class PLens<S, T, A, B>

A Lens (or Functional Reference) is an optic that can focus into a structure for getting, setting or modifying the focus (target).

A (polymorphic) PLens is useful when setting or modifying a value for a constructed type.

A PLens can be seen as a pair of functions: - get: (S) -> A meaning we can focus into S and extract an A. - set: (B, S) -> T meaning we can focus into an S and set a value B for a target A and obtain a modified source.

The type arguments are: - S is the source of a PLens. - T is the modified source of a PLens. - A is the focus of a PLens. - B is the modified focus of a PLens.

  • Composes a PLens with a PLens.

    Declaration

    Swift

    public static func + <C, D>(lhs: PLens<S, T, A, B>, rhs: PLens<A, B, C, D>) -> PLens<S, T, C, D>

    Parameters

    lhs

    Left side of the composition.
    rhs

    Right side of the composition.

    Return Value

    A PLens resulting from the sequential application of the two provided optics.

  • Composes a PLens with a PIso.

    Declaration

    Swift

    public static func + <C, D>(lhs: PLens<S, T, A, B>, rhs: PIso<A, B, C, D>) -> PLens<S, T, C, D>

    Parameters

    lhs

    Left side of the composition.
    rhs

    Right side of the composition.

    Return Value

    A PLens resulting from the sequential application of the two provided optics.

  • Composes a PLens with a Getter.

    Declaration

    Swift

    public static func + <C>(lhs: PLens<S, T, A, B>, rhs: Getter<A, C>) -> Getter<S, C>

    Parameters

    lhs

    Left side of the composition.
    rhs

    Right side of the composition.

    Return Value

    A Getter resulting from the sequential application of the two provided optics.

  • Composes a PLens with a PPrism.

    Declaration

    Swift

    public static func + <C, D>(lhs: PLens<S, T, A, B>, rhs: PPrism<A, B, C, D>) -> PAffineTraversal<S, T, C, D>

    Parameters

    lhs

    Left side of the composition.
    rhs

    Right side of the composition.

    Return Value

    A PAffineTraversal resulting from the sequential application of the two provided optics.

  • Composes a PLens with a PAffineTraversal.

    Declaration

    Swift

    public static func + <C, D>(lhs: PLens<S, T, A, B>, rhs: PAffineTraversal<A, B, C, D>) -> PAffineTraversal<S, T, C, D>

    Parameters

    lhs

    Left side of the composition.
    rhs

    Right side of the composition.

    Return Value

    A PAffineTraversal resulting from the sequential application of the two provided optics.

  • Composes a PLens with a PSetter.

    Declaration

    Swift

    public static func + <C, D>(lhs: PLens<S, T, A, B>, rhs: PSetter<A, B, C, D>) -> PSetter<S, T, C, D>

    Parameters

    lhs

    Left side of the composition.
    rhs

    Right side of the composition.

    Return Value

    A PSetter resulting from the sequential application of the two provided optics.

  • Composes a PLens with a Fold.

    Declaration

    Swift

    public static func + <C>(lhs: PLens<S, T, A, B>, rhs: Fold<A, C>) -> Fold<S, C>

    Parameters

    lhs

    Left side of the composition.
    rhs

    Right side of the composition.

    Return Value

    A Fold resulting from the sequential application of the two provided optics.

  • Composes a PLens with a PTraversal.

    Declaration

    Swift

    public static func + <C, D>(lhs: PLens<S, T, A, B>, rhs: PTraversal<A, B, C, D>) -> PTraversal<S, T, C, D>

    Parameters

    lhs

    Left side of the composition.
    rhs

    Right side of the composition.

    Return Value

    A PTraversal resulting from the sequential application of the two provided optics.

  • Initializes a PLens with its get and set functions.

    Declaration

    Swift

    public init(get: @escaping (S) -> A, set: @escaping (S, B) -> T)

    Parameters

    get

    Getter function for the lens.
    set

    Setter function for the lens.

  • Obtains the focus of this lens.

    Declaration

    Swift

    public func get(_ s: S) -> A

    Parameters

    s

    Source.

    Return Value

    Focus for the provided source.

  • Sets the focus of this lens.

    Declaration

    Swift

    public func set(_ s: S, _ b: B) -> T

    Parameters

    s

    Source.
    b

    Modified focus.

    Return Value

    Modified source.

  • Modifies the focus of this lens using a Functor function.

    Declaration

    Swift

    public func modifyF<F: Functor>(_ s: S, _ f: @escaping (A) -> Kind<F, B>) -> Kind<F, T>

    Parameters

    s

    Source.
    f

    Modifying function.

    Return Value

    Modified source in the context of the Functor.

  • Lifts a Functor function between the targets to a function between the sources.

    Declaration

    Swift

    public func liftF<F: Functor>(_ f: @escaping (A) -> Kind<F, B>) -> (S) -> Kind<F, T>

    Parameters

    f

    Modifying function between the targets.

    Return Value

    A Functor function between the sources.

  • Joins two lenses with the same focus.

    Declaration

    Swift

    public func choice<S1, T1>(_ other: PLens<S1, T1, A, B>) -> PLens<Either<S, S1>, Either<T, T1>, A, B>

    Parameters

    other

    A lens with the same focus as this one.

    Return Value

    A lens whose source is a pair of the two original lenses.

  • Pairs two disjoint lenses.

    Declaration

    Swift

    public func split<S1, T1, A1, B1>(_ other: PLens<S1, T1, A1, B1>) -> PLens<(S, S1), (T, T1), (A, A1), (B, B1)>

    Parameters

    other

    A disjoint lens.

    Return Value

    A lens that operates on tuples of the original and parameter sources and targets.

  • Pairs this PLens with another type, placing this as the first element.

    Declaration

    Swift

    public func first<C>() -> PLens<(S, C), (T, C), (A, C), (B, C)>

    Return Value

    A PLens that operates on tuples where the second argument remains unchanged.

  • Pairs this PLens with another type, placing this as the second element.

    Declaration

    Swift

    public func second<C>() -> PLens<(C, S), (C, T), (C, A), (C, B)>

    Return Value

    A PLens that operates on tuples where the first argument remains unchanged.

  • Composes this lens with a PLens.

    Declaration

    Swift

    public func compose<C, D>(_ other: PLens<A, B, C, D>) -> PLens<S, T, C, D>

    Parameters

    other

    Value to compose with.

    Return Value

    A PLens resulting from the sequential application of the two optics.

  • Composes this lens with a PIso.

    Declaration

    Swift

    public func compose<C, D>(_ other: PIso<A, B, C, D>) -> PLens<S, T, C, D>

    Parameters

    other

    Value to compose with.

    Return Value

    A PIso resulting from the sequential application of the two optics.

  • Composes this lens with a Getter.

    Declaration

    Swift

    public func compose<C>(_ other: Getter<A, C>) -> Getter<S, C>

    Parameters

    other

    Value to compose with.

    Return Value

    A Getter resulting from the sequential application of the two optics.

  • Composes this lens with a PPrism.

    Declaration

    Swift

    public func compose<C, D>(_ other: PPrism<A, B, C, D>) -> PAffineTraversal<S, T, C, D>

    Parameters

    other

    Value to compose with.

    Return Value

    A PAffineTraversal resulting from the sequential application of the two optics.

  • Composes this lens with a PAffineTraversal.

    Declaration

    Swift

    public func compose<C, D>(_ other: PAffineTraversal<A, B, C, D>) -> PAffineTraversal<S, T, C, D>

    Parameters

    other

    Value to compose with.

    Return Value

    A PAffineTraversal resulting from the sequential application of the two optics.

  • Composes this lens with a PSetter.

    Declaration

    Swift

    public func compose<C, D>(_ other: PSetter<A, B, C, D>) -> PSetter<S, T, C, D>

    Parameters

    other

    Value to compose with.

    Return Value

    A PSetter resulting from the sequential application of the two optics.

  • Composes this lens with a Fold.

    Declaration

    Swift

    public func compose<C>(_ other: Fold<A, C>) -> Fold<S, C>

    Parameters

    other

    Value to compose with.

    Return Value

    A Fold resulting from the sequential application of the two optics.

  • Composes this lens with a PLens.

    Declaration

    Swift

    public func compose<C, D>(_ other: PTraversal<A, B, C, D>) -> PTraversal<S, T, C, D>

    Parameters

    other

    Value to compose with.

    Return Value

    A PTraversal resulting from the sequential application of the two optics.

  • Obtains a Getter from this lens.

    Declaration

    Swift

    public var asGetter: Getter<S, A> { get }

  • Obtains a PAffineTraversal from this lens.

    Declaration

    Swift

    public var asAffineTraversal: PAffineTraversal<S, T, A, B> { get }

  • Obtains a PSetter from this lens.

    Declaration

    Swift

    public var asSetter: PSetter<S, T, A, B> { get }

  • Obtains a Fold from this lens.

    Declaration

    Swift

    public var asFold: Fold<S, A> { get }

  • Obtains a PTraversal from this lens.

    Declaration

    Swift

    public var asTraversal: PTraversal<S, T, A, B> { get }

  • Modifies the focus of this lens with the provided function.

    Declaration

    Swift

    public func modify(_ s: S, _ f: @escaping (A) -> B) -> T

    Parameters

    s

    Source.
    f

    Modifying function.

    Return Value

    Modified source.

  • Lifts a function that modifies the targets, to a function that modifies the sources.

    Declaration

    Swift

    public func lift(_ f: @escaping (A) -> B) -> (S) -> T

    Parameters

    f

    Modifying function.

    Return Value

    Function that modifies sources.

  • Retrieves the target of this lens if it matches a predicate.

    Declaration

    Swift

    public func find(_ s: S, _ predicate: (A) -> Bool) -> Option<A>

    Parameters

    s

    Source.
    predicate

    Testing predicate.

    Return Value

    An optional value that is present if the source matches the predicate.

  • Checks if the target of this lens matches a predicate.

    Declaration

    Swift

    public func exists(_ s: S, _ predicate: (A) -> Bool) -> Bool

    Parameters

    s

    Source.
    predicate

    Testing predicate.

    Return Value

    Boolean value indicating if the target of the provided source matches the predicate.

  • Extracts the value viewed through the get function.

    Declaration

    Swift

    public func ask() -> Reader<S, A>

    Return Value

    A Reader from source to target.

  • Extracts the value viewed through the get function.

    Declaration

    Swift

    public func toReader() -> Reader<S, A>

    Return Value

    A Reader from source to target.

  • Extracts the value viewed through the get function and applies the provided function to it.

    Declaration

    Swift

    public func asks<C>(_ f: @escaping (A) -> C) -> Reader<S, C>

    Parameters

    f

    Function to apply to the focus.

    Return Value

    A Reader from source to the target modified by the provided function.

  • Extracts the focus view through the PLens.

    Declaration

    Swift

    public func extract() -> State<S, A>

    Return Value

    A State of the source and target.

  • Extracts the focus view through the PLens.

    Declaration

    Swift

    public func toState() -> State<S, A>

    Return Value

    A State of the source and target.

  • Extracts the focus view through the PLens and applies the provided function to it.

    Declaration

    Swift

    public func extractMap<C>(_ f: @escaping (A) -> C) -> State<S, C>

    Return Value

    A State of the source and target, modified by the provided function.

Extensions for monomorphic Lens

  • Combine this lens with another with the same source but different focus.

    Declaration

    Swift

    func merge<AA, BB>(_ other: PLens<S, S, AA, BB>) -> PLens<S, S, (A, AA), (B, BB)>

    Parameters

    other

    A lens with the same source but different focus.

    Return Value

    A lens that lets us focus on the two foci at the same time.