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Functional Java is an open source library that supports closures for the Java programming language
package fj.data.optic;
import fj.F;
import fj.Function;
import fj.data.Either;
/**
* A {@link PSetter} is a generalisation of Functor map: - `map: (A => B) => F[A] => F[B]` - `modify: (A => B) => S =>
* T`
*
* {@link PSetter} stands for Polymorphic Setter as it set and modify methods change a type `A` to `B` and `S` to `T`.
*
* {@link PTraversal}, {@link POptional}, {@link PPrism}, {@link PLens} and {@link PIso} are valid {@link PSetter}
*
* @param the source of a {@link PSetter}
* @param the modified source of a {@link PSetter}
* @param the target of a {@link PSetter}
* @param the modified target of a {@link PSetter}
*/
public abstract class PSetter {
PSetter() {
super();
}
/** modify polymorphically the target of a {@link PSetter} with a function */
public abstract F modify(F f);
/** set polymorphically the target of a {@link PSetter} with a value */
public abstract F set(final B b);
/** join two {@link PSetter} with the same target */
public final PSetter, Either, A, B> sum(final PSetter other) {
return pSetter(f -> e -> e.bimap(modify(f), other.modify(f)));
}
/*************************************************************/
/** Compose methods between a {@link PSetter} and another Optics */
/*************************************************************/
/** compose a {@link PSetter} with a {@link PSetter} */
public final PSetter composeSetter(final PSetter other) {
final PSetter self = this;
return new PSetter() {
@Override
public F modify(final F f) {
return self.modify(other.modify(f));
}
@Override
public F set(final D d) {
return self.modify(other.set(d));
}
};
}
/** compose a {@link PSetter} with a {@link PTraversal} */
public final PSetter composeTraversal(final PTraversal other) {
return composeSetter(other.asSetter());
}
/** compose a {@link PSetter} with a {@link POptional} */
public final PSetter composeOptional(final POptional other) {
return composeSetter(other.asSetter());
}
/** compose a {@link PSetter} with a {@link PPrism} */
public final PSetter composePrism(final PPrism other) {
return composeSetter(other.asSetter());
}
/** compose a {@link PSetter} with a {@link PLens} */
public final PSetter composeLens(final PLens other) {
return composeSetter(other.asSetter());
}
/** compose a {@link PSetter} with a {@link PIso} */
public final PSetter composeIso(final PIso other) {
return composeSetter(other.asSetter());
}
public static PSetter pId() {
return PIso. pId().asSetter();
}
public static PSetter, Either, S, T> pCodiagonal() {
return pSetter(f -> e -> e.bimap(f, f));
}
public static PSetter pSetter(final F, F> modify) {
return new PSetter() {
@Override
public F modify(final F f) {
return modify.f(f);
}
@Override
public F set(final B b) {
return modify.f(Function.constant(b));
}
};
}
}