tiinvo/Fn.js

A library of types and utilities for your TypeScript and JavaScript projects

//#endregion
/**
 * A function which returns it's first argument.
 *
 * Use it only as a placeholder
 *
 * @example
 *
 * ```ts
 * import { Fn } from 'tiinvo'
 *
 * Fn.pass(10)      // 10
 * Fn.pass(20)      // 20
 * ```
 *
 * @since 4.0.0
 */
export const pass = (a) => a;
export function cmp(a, b) {
    const _cmp = (x, y) => {
        const namea = x.name.toLowerCase();
        const nameb = y.name.toLowerCase();
        return Math.min(Math.max((x.length > y.length ? 1 : x.length < y.length ? -1 : 0) +
            (namea > nameb ? 1 : namea < nameb ? -1 : 0), -1), 1);
    };
    if (guard(a) && guard(b)) {
        return _cmp(a, b);
    }
    return (b) => _cmp(b, a);
}
;
export function eq(a, b) {
    if (guard(a) && guard(b)) {
        return a === b && cmp(a, b) === 0;
    }
    return (b) => b === a && cmp(b, a) === 0;
}
//#endregion
//#region accessors
/**
 * Returns a function arguments length
 *
 * @example
 *
 * ```ts
 * import { Fn } from 'tiinvo'
 *
 * Fn.length(Fn.cmp)        // 2
 * Fn.length(Fn.length)     // 1
 * ```
 *
 * @param x the function
 * @returns arguments count
 * @since 4.0.0
 */
export const length = x => x.length;
/**
 * Returns a function's name
 *
 * @example
 *
 * ```ts
 * import { Fn } from 'tiinvo'
 *
 * Fn.name(Fn.cmp)        // 'cmp'
 * Fn.name(Fn.name)       // 'name'
 * ```
 *
 * @param x the function
 * @returns the name
 * @since 4.0.0
 */
export const name = x => x.name;
//#region guardables
/**
 * Checks if an argument `x` is `AnyFn`
 *
 * @example
 *
 * ```ts
 * import { Fn } from 'tiinvo'
 *
 * Fn.guard(10)         // false
 * Fn.guard(() => {})   // true
 * ```
 *
 * @param x the value to guard
 * @returns
 *  - `true` if `x` is a function
 *  - `false` otherwise
 * @since 4.0.0
 */
export const guard = (x) => typeof x === 'function';
//#endregion
//#region mappables
/**
 * Maps a value `a` over a list of `Functors.Mappable<a, b>` and returns an array of the returning values
 *
 * @example
 *
 * ```ts
 * import { Fn, Num } from 'tiinvo'
 *
 * const m = Fn.map(
 *    Num.add(1),
 *    Num.mul(2),
 *    Num.sub(3),
 *    Num.pow(4),
 * )
 *
 * m(2)   // [3, 4, -1, 16]
 * ```
 *
 * @param ml a list of unary functions which accept the same argument
 * @return an array of the returning values of `ml`
 * @since 4.0.0
 */
export const map = (...ml) => (a) => ml.map(f => f(a));
//#endregion