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Low overhead, protected views over Java collections

There is a newer version: 1.2.3

package dev.marksman.collectionviews;

import com.jnape.palatable.lambda.adt.Maybe;
import com.jnape.palatable.lambda.functions.Fn1;
import dev.marksman.enhancediterables.ImmutableFiniteIterable;

import java.util.Objects;

import static com.jnape.palatable.lambda.adt.Maybe.just;
import static com.jnape.palatable.lambda.adt.Maybe.nothing;
import static dev.marksman.collectionviews.Validation.*;

final class RepeatingVector extends ConcreteVector
        implements ImmutableNonEmptyVector, Primitive {
    private final int size; // must be >= 1
    private final A value;

    RepeatingVector(int size, A value) {
        assert (size >= 1);
        this.size = size;
        this.value = value;
    }

    @Override
    public A head() {
        return value;
    }

    @Override
    public ImmutableFiniteIterable filter(Fn1 predicate) {
        return takeWhile(predicate);
    }

    @Override
    public A last() {
        return value;
    }

    @Override
    public int size() {
        return size;
    }

    @Override
    public A unsafeGet(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException();
        }
        return value;
    }

    @Override
    public Maybe find(Fn1 predicate) {
        Objects.requireNonNull(predicate);
        if (predicate.apply(value)) {
            return just(value);
        } else {
            return nothing();
        }
    }

    @Override
    public Maybe findIndex(Fn1 predicate) {
        Objects.requireNonNull(predicate);
        if (predicate.apply(value)) {
            return just(0);
        } else {
            return nothing();
        }
    }

    @Override
    public  ImmutableNonEmptyVector fmap(Fn1 f) {
        Objects.requireNonNull(f);
        return new RepeatingVector<>(size, f.apply(value));
    }

    @Override
    public int hashCode() {
        final int h = value == null ? 0 : value.hashCode();
        int hashCode = 1;
        for (int i = 0; i < size; i++) {
            hashCode = 31 * hashCode + h;
        }
        return hashCode;
    }

    @SuppressWarnings("unchecked")
    @Override
    public boolean equals(Object o) {
        if (o instanceof RepeatingVector) {
            RepeatingVector