functionalscript/types/array/module.f.js

FunctionalScript is a purely functional subset of JavaScript

/**
 * JavaScript immutable arrays.
 *
 * @module
 */
import { map } from "../nullable/module.f.js";
export const isArray2 = (a) => a.length === 2;
const uncheckTail = (a) => a.slice(1);
const uncheckHead = (a) => a.slice(0, -1);
export const at = (i) => (a) => {
    const r = a[i];
    return r === undefined ? null : r;
};
export const first = at(0);
export const last = (a) => at(a.length - 1)(a);
export const tail = (a) => a.length === 0 ? null : uncheckTail(a);
export const splitFirst = (a) => {
    const split = (first) => [first, uncheckTail(a)];
    return map(split)(first(a));
};
export const head = (a) => a.length === 0 ? null : uncheckHead(a);
export const splitLast = (a) => {
    const lastA = last(a);
    if (lastA === null) {
        return null;
    }
    return [uncheckHead(a), lastA];
};
/**
 * An empty immutable array.
 *
 * Two JavaScript empty arrays are different and has to have two different values.
 * Usually, it requires memory allocation. If we use the same an empty array everywhere,
 * we may minimize memory a number of memory allocations.
 */
export const empty = [];