Utilities

Only a very cool Shiba would even dare use a cat's tools.

Alternative Documentation WIP.

Installation & Usage

npm -i meows
yarn add meows

import * as U from meows
import { isType, isEmpty, notEmpty } from 'meows'

const U = require('meows')
const { isType, isEmpty, notEmpty } = require('meows')

Strings

const space = ' '
const spaces = /\s+/
const character = ''
const alphabet = [ 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
   'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', ]

/** Split string by spaces. */
function split_by_spaces(str: string): string[]

/** Alphabetical character → prime number. */
function alpha_to_prime(alphabet: string): number

/**
 * word anagram → prime product
 *
 * @description
 * An anagram is any rearrangement of a string. Conveniently, the product of
 * primes is the same regardless of order, and also allows us to count how many
 * of each prime was used, acting as an identity for anagrams.
 *
 * @example
 * anagram_to_id('listen') === anagram_to_id('silent')    // => true
 * anagram_to_id('admirer') === anagram_to_id('married')  // => true
 */
function anagram_to_id(word: string): number

/**
 * Strips a string of all normal whitespaces.
 * @example
 * stripSpaces('  a  b   c ' )  // => 'abc'
 */
function stripSpaces(str:string): string

Date and Time

/** Convert an integer from 1 to 12 to a month. */
function number_to_month(integer: number): string

/** A utility to store multiple timestamps for performance timing. */
class Timer {
   // The full state of the Timer object.
   _log(): { label: string, time: number }[]

   // A list of Unix timestamps.
   _times(): number[]

   // Add a midpoint to timer with optional label.
   next(label: string): void

   // Start timer with optional label.
   start(label: string): void

   // Add endpoint to timer with optional label.
   end(label: string): void

   // range :: () → integer || NaN if fewer than 2 timestamps.
   range(): number

   // delta :: () → integer[]
   delta(): number[]

   // Returns array of relative difference of time from start, unix timestamp as first entry.
   // relative :: () → integer[]
   relative(): number[]
}

Error and Logging

/** Alias for `console.log()`. */
function log(...a: any[]): void

/** `console.log()` with an introductory string message. */
function logStr(msg?: string, ...a: any[]): void

/**
 * Log something to console with optional message, then returns identical input.
 *
 * @example
 * Promise.all(pending)
 *    .then(x => logId(x, 'task: done'))
 *    .then(sendTask)
 */
function logId(x: any, msg?:string): any

Arrays

/**
 * A function for quickly generating arrays populated by a range of integers,
 * with an optional skip interval.
 * 
 * @example
 * range(3)          // => [0, 1, 2, 3]
 * range(-3)         // => [0, -1, -2, -3]
 * range(-2, 2)      // => [-2, -1, 0, 1, 2]
 * range(2, -2)      // => [2, 1, 0, -1, -2]
 * range(-10, 10, 5) // => [-10, -5, 0, 5, 10]
 * range(10, -10, 5) // => [10, 5, 0, -5, -10]
 */
function range(p0:number, pf?:number, speed?:number): number[]

/** 
 * Shallow filters out redundant members.
 * @example
 * uniques([0, 1, 2, 2, 3, 3])  // => [0, 1, 2, 3]
 */
function uniques(arr?: any[]): any[]

/** 
 * Shallow checks for repeat members.
 * @example
 * has_repeat([1, 2, 3])  // => false
 * has_repeat([1, 2, 1])  // => true
 */
function hasRepeat(arr: any[]): boolean

/** 
 * Choose random member in array. 
 * @example 
 * rand_choice([1, 'a', null])  // => 1
 * rand_choice([1, 'a', null])  // => null
 */
function randChoose(arr?: any[]): any

/**
 * Uses `λ` to populate an array of `size` length.
 * 
 * @example
 * series(x => 0.5*x**2 + 0.5*x, 5)  // => [0, 1, 3, 6, 10]
 */
function series(λ:Function, size:number): any[]

/**
 * Returns a shallow copy of the last value of your array. The default behavior
 * is to return `undefined` on an empty array while `throwOnEmpty` is set to
 * `false`.
 *
 * @example
 * last([3, 2, 1])       // => 1
 * last([3, 2, [1, 0]])  // => [1, 0]
 * last([null])          // => null
 * last([])              // => undefined if throwOnEmpty is false (!)
 */
function last(arr: any[], throwOnEmpty?: boolean): any

Objects

/** An empty object with no prototype. */
type ONULL = object

/** Flip the binary value for a property on an object. */
function flipProp(prop: string, obj: object): object

/** Merge objects with an empty object; can be used to strip prototype. */
function merge(...objs: object[])

/** Grab an object based on pathway of sequence of keys.
 * @example
 * const store = {
 *    a: 0,
 *    b: {
 *       a: [0, 0, 0],
 *       b: 1,
 *    }
 * }
 * const node = path(store, 'a', 'b', 'a')
 * const value = node[0]
 *
 * node[0] = 1
 * console.log(store.a.b.a)  // => [1, 0, 0]
 * console.log(value * 2)    // => 2
 */
function path(obj: object, ...props: string[]): any

Functions

/** composes a sequence of functions from right to left. */
function compose(...fns: Function[]): Function

/** composes a sequence of functions from left to right. */
function pipe(...fns: Function[]): Function

/** zip, but with a function */
function zipWith(λ: Function, v1: any[], v2: any[]): any[]

/**
 * @example
 * [true, true, false].filter(identity)  // => [true, true]
 */
function identity(x: any): any

/**
 * Given a lambda and a value `x`, run the lambda with optional arguments as a 
 * side effect, and then return the original given value `x`.
 * 
 * @example
 * function sayHi(msg = 'hi') { console.log(msg) }
 * effectId(sayHi, 42)        // => logs 'hi' and returns 42
 * effectId(sayHi, 42, 'yo')  // => logs 'yo' and returns 42
 */
function effectId(λ:Function, x, ...args)

/**
 * See if at least one array element
 * @example
 * const v1 = [2, 4, 6, 8]
 * const v2 = [2, 4, 6, 9]
 * const even = x => x % 2 === 0
 *
 * count(even, v1)  // => 4
 * count(even, v2)  // => 1
 * count(even, [])  // => 0
 */
function count(λ: Function, arr: any[]): number  | TypeError

/**
 * Given λ → returns `(compose not λ)`.
 * @example
 * const notArray = not(Array.isArray)
 * notArray([])  // => false
 * notArray({})  // => true
 */
function not(λ: Function): (...args: any[]) => boolean

/**
 * Checks if an array is a non-empty array of things that would always pass
 * your boolean function. Like `orMap` or `.every()` except empty arrays return
 * false.
 *
 * @example
 * always(even, [0, 2, 4])  // => true
 * always(even, [0, 1, 2])  // => false
 * always(even, [])         // => false
 */
function always(cond: Function, arr: any[]): boolean

/**
 * Coerces values to `true`. If input is a function, `truthy` will run the
 * function with optional arguments for side effects before returning `true`.
 
 * @example
 * truthy(console.log('hi')) && 42 // logs 'hi' and returns 42
 *
 * const say = (msg='hi') => console.log(msg)
 * truthy(say)        // logs 'hi' and returns true
 * truthy(say, 'yo')  // logs 'yo' and returns true
 */
function truthy(λ: Function, ...arg: any[]): boolean

/**
 * Coerces values to `false`. If input is a function, `falsy` will run the
 * function with optional arguments for side effects before returning `false`
 *
 * @example
 * falsy(console.log('hi')) || 42 // logs 'hi' and returns 42
 *
 * const say = (msg='hi') => console.log(msg)
 * falsy(say)        // logs 'hi' and returns false
 * falsy(say, 'yo')  // logs 'yo' and returns false
 */
function falsy(λ: Function, ...arg: any[]): boolean

Numbers and Random

/**
 * A suite of random tools.
 *
 * @example
 * Rand.int()   // => -42
 * Rand.real()  // => -42.42
 * Rand.bool() ? 'heads' : 'tails'
 * Rand.sBool() ? 'heads' : 'tails'
 */
class Rand {
   static int(min?:number, max?:number): number
   static real(min?:number, max?:number): number
   /**
    * Returns a weak random boolean.
    */
   static wBool(): boolean
   /**
    * Given natural `n` ⟶ returns `n` 'strong' random booleans.
    * @example
    * Rand.sBool() ? 'heads' : 'tails'
    * Rand.sBool(10).filter(x => x)
    */
   static bool(natural: number): boolean
}

/** Generate an array of `n` strong random integers. */
function randomInts(n: number): number[]

/** Sums numeric arguments. */
function sum(nums: number[]): number

/** Multiplies numeric arguments. */
function product(nums: number[]): number

/** Finds the difference in magnitude between two numbers. */
function diff_abs(a: number, b: number): number

/** Finds the delta of unidimensional array of reals. */
function diff_nums(nums: number[]): number[]

/** Converts an integer to an array of its digits.
 * @example
 * int_to_digits(123450)  // => [1, 2, 3, 4, 5, 0]
 */
function int_to_digits(int:number, base?:number): number[]

/**
 * Randomly signs a signable number. If the value isn't signable, return `NaN`.
 * @example
 * const backoff = (tries) => 2**tries + plus_or_minus(Math.random())
 */
function plus_or_minus(num: number): number

function negative(num: number): number
function positive(num: number): number
function flipSign(num: number): number

Logic and Types

class notEmpty {
   /**
    * @example
    * notEmpty.arr([])      // => false
    * notEmpty.arr({a: 1})  // => false
    */
   static arr(x): boolean
   /**
    * @example
    * notEmpty.obj([1, 2])  // => false
    * notEmpty.obj({})      // => false
    */
   static obj(x): boolean
   /**
    * @example
    * notEmpty.str(null)  // => false
    * notEmpty.str('')    // => false
    * notEmpty.obj(' ')   // => true
    */
   static str(x): boolean
   /**
    * @example
    * const empty = new Map()
    * const full = new Map().set('animal', 'cat')
    * 
    * notEmpty.map(full)   // => true
    * notEmpty.map(empty)  // => false
    * notEmpty.map({})     // => false
    * notEmpty.map([])     // => false
    */
   static map(x): boolean
}

/**
 * Class of static boolean functions for finding whether a value <is> an empty
 * instance of a type.
 */
class isEmpty {
   /**
    * @example
    * isEmpty.arr({})  // => false
    * isEmpty.arr([0]) // => false
    * isEmpty.arr([])  // => true
    */
   static arr(x): boolean
   /**
    * @example
    * isEmpty.obj([])     // => false
    * isEmpty.obj({a: 1}) // => false
    * isEmpty.obj({})     // => true
    */
   static obj(x): boolean
   /**
    * @example
    * isEmpty.str([])    // => false
    * isEmpty.str('  ')  // => false
    * isEmpty.str('')    // => true
    */
   static str(x): boolean
   /**
    * @example
    * const empty = new Map()
    * const full = new Map().set('animal', 'cat')
    * 
    * isEmpty.map(empty)  // => true
    * isEmpty.map(full)   // => false
    * isEmpty.map({})     // => false
    * isEmpty.map([])     // => false
    */
   static map(x): boolean
}

/**
 * Class of static boolean functions for determining non-canonical subtypes in
 * JavaScript, such as reals or signable 'numbers'.
 * 
 * @example
 * isType.num(1/0)   // => false
 * isType.int(3.0)   // => true
 * isType.real(3)    // => true
 * isType.err(NaN)   // => false
 */
class isType {
   /** Excludes NaN and Infinity! */
   static num(x?): boolean
   /** Checks if number is positive integer, including 0. */
   static nat(x?): boolean
   /** Only safe integers. */
   static int(x?): boolean
   /** Check if value is a string. */
   static str(x?): boolean
   /** Check if value is a function. */
   static fn(x?): boolean
   /** 
    * Any signable number including neutral 0, but excluding NaN and null. 
    * @example
    * isType.signable(0)     // => true
    * isType.signable(1/0)   // => true
    * isType.signable(-5)    // => true
    * isType.signable({})    // => false
    * isType.signable(NaN)   // => false
    * isType.signable(null)  // => false
    */
    static signable(x?): boolean
    /**
     * Checks if value is an error object.
     * @example
     * isType.err(new TypeError())  // => true
     * isType.err({})               // => false
     * isType.err(null)             // => false
     */
    static err(x?): boolean
    /**
     * Checks if value is a negative number, excluding `0`, and `Infinity`.
     * @example
     * isType.neg(-2)    // true
     * isType.neg(+2)    // false
     * isType.neg(-0)    // false (!)
     * isType.neg(-1/0)  // false (!)
     * isType.neg([])    // false
     * isType.neg(NaN)   // false
     */
    static neg(x?): boolean
    /**
     * Checks if value is an instance of Map.
     * 
     * @example
     * isType.map(new Map())  // => true
     * isType.map({})         // => false
     * isType.map([])         // => false
     */
    static map(x?): boolean
}


/**
 * Returns the type of an unknown value as a lower-cased string. Type 'number'
 * is defined separately from 'infinity' and 'nan' because most functions on
 * numbers don't expect those types.
 *
 * @example
 * typeName(new Map)  // => 'map'
 * typeName(void f()) // => 'undefined'
 * typeName(null)     // => 'null'
 * typeName([])       // => 'array'
 * typeName({})       // => 'object'
 * typeName(/\s+/)    // => 'regexp'
 * typeName(0 / 0)    // => 'nan'
 * typeName(-1 / 0)   // => 'infinity'
 *
 * const buffer = new ArrayBuffer(16)
 * const view = new Int16Array(buffer)
 * const err = new Error()
 *
 * typeName(err)    // => 'error'
 * typeName(buffer) // => 'arraybuffer'
 * typeName(view)   // => 'int16view'
 */
function typeName(x?: any): string

Async

/**
 * Promisified setTimeout that resolves to `<any>` or `<void>`.
 * @example
 * // logs 'hi' after delay
 * let hi = async () => await wait(4000, 'hi')
 *    .then(console.log)
 */
function wait(ms?:number, resolveTo?:any): Promise <any>