Predicate truthy Function via %check

Description

This is a Flow helper library for Lodash is and additional Flow predicate type %checks functions. Simply put, this library contains converted truthy predicate functions through the use of Flow %check annotations. By doing so it aids and increases the ability for The Flow Parser to properly check the defined predicate functions.

Why?

Flow and Lodash's predicate functions (is***) don't work well together (if at all in some cases) resulting in duplicate logic. Ideally a fix will be implemented into the main flow-type Lodash library but until that time comes (if ever) this library acts as a stopgap solution. In addition, this library includes some helpful custom predicate check functions.

Install

# npm
npm i --save @cursormove/flow-is-helpers

# yarn
yarn add @cursormove/flow-is-helpers

Usage

This Library is a drop-in replacement for Lodash's predicate functions. You should be able to just swap out Lodash predicate functions like isString with this library. I recommend you take a quick look at the code base just so you have a better understanding of what is going on but the gist of it is pretty simple.

import {
  isString,
} from '@cursormove/flow-is-helpers';

// Flow Type Check & truthy predicate function check
const hello = (val: string) => isString(val) ? `Hello ${val}` : 'Hello Nobody';

hello('World'); // 'Hello World' 
hello(null); // 'Hello Nobody'

API 🠲 Custom Checks

Array Checks

• isEmptyArray 🠲 Checks if Array is empty.
• isNonEmptyArray 🠲 Checks if Array is empty.

Function Checks

• isPromise 🠲 Checks if Function type is a Promise.
• isAsync 🠲 Checks if Function type is Async.
• isGenerator 🠲 Checks if Function type is a Generator Iterator.
• isGeneratorFunction 🠲 Checks if Function type is a Generator.

Plain Object Checks (Not ObjectLike)

• isEmptyObject 🠲 Checks if Object is empty.
• isNonEmptyObject 🠲 Checks if Object is not empty.
• isFrozen 🠲 Checks if Object is Frozen.
• isFrozen 🠲 Checks if Object is Sealed.
• isFrozen 🠲 Checks if Object is Extensible.

String Checks

• isEmptyString 🠲 Checks if String is empty.
• isNonEmptyString 🠲 Checks if String is not empty.

Number Checks

• isNan 🠲 Checks if value is not a Number.
• isInfinity 🠲 Checks if value is either Number.NEGATIVE_INFINITY or Number.POSITIVE_INFINITY.

Nil Checks

• isNotNil 🠲 Opposite of Lodash's isNil in that it's not null or undefined.

Miscellaneous Checks

• isIterable 🠲 Checks if value is an Iterable
• isAction 🠲 Checks if value is a Redux Action

API 🠲 Lodash Checks

Includes all Lodash is Predicate Functions

• isArguments
• isArray
• isArrayBuffer
• isArrayLike
• isArrayLikeObject
• isBoolean
• isBuffer
• isDate
• isElement
• isEmpty
• isEqual
• isEqualWith
• isError
• isFinite
• isFunction
• isInteger
• isLength
• isMap
• isMatch
• isMatchWith
• isNaN
• isNative
• isNil
• isNull
• isNumber
• isObject
• isObjectLike
• isPlainObject
• isRegExp
• isSafeInteger
• isSet
• isString
• isSymbol
• isTypedArray
• isUndefined
• isWeakMap
• isWeakSet

Best, te