hofkit

hofkit (Higher Order Function toolKIT) is a modular functional utility library for JavaScript & TypeScript. This library collects frequently rewritten experimental functional wrappers for commonly used utility functions (either custom or from popular libraries such as lodash). These wrappers emphasised functional concepts (e.g., higher order functions, state purity, etc.) to provide functional benefits (e.g., less state, composition) whilst preserving compatibility with existing imperative approaches.

Through this flexiblity, the toolkit aims to be reusable across projects for a wide variety of uses ranging from array & object manipulation (e.g., filtering object entries) to concurrency-controlled Promises.

Additional benefits include builtin type support, environment-specific modules (i.e., featureGroups that group functions to separate dependencies), live-reloadable per-function test suites, and auto-generated live-reloadable documentation.

Features

Feature	Details
Provide a library of functional utility functions	Includes 164 core functions & 14 node-environment functions (as of initial release), that cover a variety of uses ranging from array & object manipulation (e.g., filtering object entries) to concurrency-controlled Promises
Compatible with function & imperative approaches	Provides functional benefits (e.g., purity, composition) whilst remaining compatibility with imperative implementations
Interoperable with JavaScript & TypeScript	-
Builtin TypeScript support for all functions	All functions are written in TypeScript to generate bundled environment-specific declaration files
Typed return values for functional composition	-
Auto-generated live-reloadable documentation	Documentation is generated & live-reloadable for all featureGroup functions, which includes type signatures & any manual documentation
Modular environment-specific functions	Environment-specific functions are grouped into individually importable featureGroup modules (e.g., core, node, etc.) to separate dependencies
Environment-specific per-function unit test suites	All functions are easily testable via dedicated environment grouped live-reloadable test suites (totalling 180 test suites & 614 tests as of initial release)
Supports testing curried functions via command line	See test:cli in Scripts
Consistent code via JavaScript & TypeScript linting	Uses eslint-config-jsx to ensure consistent code

Usage

Install:

npm install hofkit

Using core functions in TypeScript:

import * as H from 'hofkit'; // Import all `core` functions.
// JavaScript: const H = require('hofkit');

import { titleCase } from H; // Named import.
// JavaScript: const { titleCase } = H;

titleCase('foo bar'); //=> 'Foo Bar'

// Typed return value: `toTitle: any => string`.
const toTitle = H.compose(
    titleCase,
    H.trim,
);
toTitle(' Foo-barBaz '); //=> 'Foo Bar Baz'

Using modular environment-specific functions (currently only node is supported), e.g., node functions:

import * as H from 'hofkit';
import * as HN from 'hofkit/dist/node'; // Import all `node` functions (requires Node environment).
import { readFile } from HN; // Named import.

// Using `async` IFFE for clarity but can be replaced by `H.promiseTryOr` to handle errors.
(async () => {
    // Writing to a file.
    await HN.writeFile('path/to/file')('foo');

    // Find existing paths.
    const filePaths = ['path1', 'path2', 'path3']; // Several file paths.
    const existingFilePaths = await H.promiseFilter(HN.pathExists);

    // Reading data for all existing files.
    let contents: string[] = [];
    const poolSize = 10;
    const onPoolComplete = (poolData: string) => [...contents, ...poolData]; // Flattens data from pools.
    const toFileContents = H.compose(
        H.promiseAll(poolSize, onPoolComplete), // Controlled concurrency.
        H.map(readFile)
    );
    toFileContents(existingFilePaths); //=> [['content1', ...], ...]

    // Overwriting all files.
    const writeFoo = (filePath: string) => HN.writeFile(filePath)('foo');
    const overwriteExistingFiles = H.compose(
        H.promiseAll(), // Uncontrolled concurrency;
        H.map(HN.writeFoo)
    );
    overwriteExistingFiles(filePaths);
})();

Documentation

Function documentation is available via the documentation website.

Screenshot of core documentation website:

Scripts

Script	Info
test	Run all tests
test:core	Run all core feature group tests
test:node	Run all node feature group tests
test <...test-names>	Run tests matching test-names
test:watch	Run all tests in watch mode
test:cli <functionName> <...argSets>	Runs a function matching functionName with argSets (see runFunctionFromCli.ts)
test:data:reset	Resets the test data directory (i.e., _testDataDir/) & its contents
docs:clean	Remove existing docs
docs:build	Output documentation to docs/
docs:build:serve	Output & serve docs
docs:serve	Serve existing docs in watch mode
docs:serve:open	Open served docs
docs:watch	Output docs in watch mode
docs:watch:serve	Output & serve docs in watch mode
build:clean	Removes the generated dist/ directory
build:featureGroupIndexes	Updates all feature group index.ts files (i.e., updates exported functions, see updateFeatureGroupIndexes.ts)
build	Generates the production dist/ directory & its contents (minified bundles, bundled declarations, etc.)
build:dev	Development alternative to build
pack:clean	Removes generated tarball files
pack	Runs pack:clean before re-generating a tarball file containing npm required (e.g., package.json) & generated files (i.e., _dist/
pack:dry	Same as pack but prints tarball file contents without generating the tarball file
deploy:pre	Runs all pre-deploy scripts (e.g., test, build, pack, etc.)
deploy:major	Runs deploy:pre before publishing an incremented major version
deploy:minor	Runs deploy:pre before publishing an incremented minor version
deploy:patch	Runs deploy:pre before publishing an incremented patch version
deploy	Runs deploy:pre before publishing the current version

Future Plans

• Complete remaining spec functions
• Test async composition
• Support web environments (e.g., browser, react, etc.)
• Changelog