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x/ramda/comparator.js

:ram: Practical functional Javascript
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import _curry1 from './internal/_curry1';

/** * Makes a comparator function out of a function that reports whether the first * element is less than the second. * * @func * @memberOf R * @since v0.1.0 * @category Function * @sig ((a, b) -> Boolean) -> ((a, b) -> Number) * @param {Function} pred A predicate function of arity two which will return `true` if the first argument * is less than the second, `false` otherwise * @return {Function} A Function :: a -> b -> Int that returns `-1` if a < b, `1` if b < a, otherwise `0` * @example * * const byAge = R.comparator((a, b) => a.age < b.age); * const people = [ * { name: 'Emma', age: 70 }, * { name: 'Peter', age: 78 }, * { name: 'Mikhail', age: 62 }, * ]; * const peopleByIncreasingAge = R.sort(byAge, people); * //=> [{ name: 'Mikhail', age: 62 },{ name: 'Emma', age: 70 }, { name: 'Peter', age: 78 }] */var comparator = _curry1(function comparator(pred) { return function(a, b) { return pred(a, b) ? -1 : pred(b, a) ? 1 : 0; };});export default comparator;