expressive-ts is a functional programming library designed to simplify building complex regular expressions.

Expressive-ts

Table of contents

• Installation
• Why?
• Usage
• Documentation
• Prior Art

Installation

npm install fp-ts expressive-ts

or

yarn add fp-ts expressive-ts

Note: fp-ts is a peer dependency of expressive-ts

Why?

The expressive nature of the expressive-ts API makes it incredibly easy to understand the purpose of an otherwise cryptic regular expression. Function composition is a core component of the API. By composing together the various functions provided by expressive-ts, extremely complex regular expressions can be built easily.

Usage

Lets imagine that we would like to recognize and validate a basic URL. Here's how it would look using expressive-ts.

import { pipe } from 'fp-ts/lib/function'
import * as E from 'expressive-ts/lib/Expression'

const expression = pipe(
  E.compile, // expressions always begin with a call to `compile`
  E.startOfInput,
  E.string('http'),
  E.maybe('s'),
  E.string('://'),
  E.maybe('www.'),
  E.anythingBut(' '),
  E.endOfInput,
  E.toRegex
)

assert.strictEqual(expression.test('https://www.google.com'), true)
assert.strictEqual(expression.test('https://google.com'), true)
assert.strictEqual(expression.test('http://google.com'), true)
assert.strictEqual(expression.test('http:/google.com'), false)
assert.strictEqual(expression.test('http://goog le.com'), false)

Documentation

• Docs

Prior Art

• Super Expressive (@francisrstokes)
• Verbal Expressions (@VerbalExpressions)