com.mojang.datafixers.optics

Interface Adapter<S,T,A,B>

Type Parameters:

S - The input object type.

T - The output object type.

A - The input field type.

B - The output field type.

All Superinterfaces:

Adapter<S::A,T::B>, Optic<Profunctor _,S::A,T::B>

public interface Adapter<S,T,A,B>
extends Optic<Profunctor _,S::A,T::B>

An adapter is an optic that defines an invertible transformation between the input and output types. It provides functionality to extract a value A from the input object S and to create an output object T from an output field B.

The canonical example of an adapter is boxing and unboxing.

In order to be a lawful adapter, the implementations of from(Object) and to(Object) must satisfy certain requirements. Assume that the object types S and T are implicitly convertible between each other and that the field types A and B are similarly convertible. Then the following rules must hold (== here represents logical equality and not reference equality).

1. from(to(b)) == b - Round-tripping a field yields the input.
2. to(from(s)) == s - Round-tripping an object yields the input.

Adapter optics that are not lawful are said to be either neutral or chaotic, depending on the degree to which the adapter laws are broken.

Type Shape:

%.Type.[%0::%2,%1::%3]

API Note:

An adapter is a special case of a Prism, and is sometimes called an Iso.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	Adapter.Instance<A2,B2> The Profunctor type class instance for Adapter.

Nested classes/interfaces inherited from interface com.mojang.datafixers.optics.Optic

Optic.CompositionOptic<Proof extends K1,S,T,A,B,A1,B1>

Method Summary

Modifier and Type	Method and Description
default <P extends K2> (P<A,B>) -> P<S,T>	eval(Profunctor P proofBox) Evaluates this adapter to produce a function that, when given a transformation between field types, produces a transformation between object types.
A	from(S s) Unboxes a value from the input object.
T	to(B b) Boxes a value into an output object.

Methods inherited from interface com.mojang.datafixers.optics.Optic

compose, composeUnchecked, upCast

Method Detail

from

A from(S s)

Unboxes a value from the input object.

Implementation Requirements:

The implementation must, in conjunction with to(Object), satisfy the adapter laws in order for this adapter to be a lawful adapter.

Parameters:

s - A value of the input object type.

Returns:

The unboxed value of the input field type.

to

T to(B b)

Boxes a value into an output object.

Implementation Requirements:

The implementation must, in conjunction with from(Object), satisfy the adapter laws in order for this adapter to be a lawful adapter.

Parameters:

b - A value of the output field type.

Returns:

The boxed value of the output object type.

eval

default <P extends K2> (P<A,B>) -> P<S,T> eval(Profunctor P proofBox)

Evaluates this adapter to produce a function that, when given a transformation between field types, produces a transformation between object types. The transformation unboxes a value from the input object and boxes the transformed value into an output object.

Specified by:

eval in interface Optic<Profunctor _,S::A,T::B>

Type Parameters:

P - The type of transformation.

Parameters:

proofBox - The Profunctor type class instance for the transformation type.

Returns:

A function that takes a transformation between field types and produces a transformation between object types.

See Also:

Adapter.Instance