aggregate-comparators.ts

const { find, identity, toPairs, compose, map, curry } = require('ramda');

/* tslint:disable: no-any */
type AnyType = any;
/* tslint:enable: no-any */

type TComparator = (a: AnyType, b: AnyType) => number;

type TObjectComparator = {
    [key: string]: TComparator;
}

const findOr = curry((fallback, fn, list) => find(fn, list) || fallback);

export function multiArrayComparator(comparators: TComparator[]): TComparator {
    return (x, y) => compose(
        findOr(0, identity),
        map(fn => fn(x, y))
    )(comparators);
}

export function multiObjectComparator(comparators: TObjectComparator): TComparator {
    return (x, y) => compose(
        findOr(0, identity),
        map(([key, fn]) => fn(x[key], y[key])),
        toPairs
    )(comparators);
}