Funfix NPM | npm.io

Funfix

Funfix is a library of type classes and data types for Functional Programming in JavaScript, TypeScript and Flow.

Usage

The code is organized in sub-projects, for à la carte dependencies, but all types, classes and functions are exported by funfix, so to import everything:

npm install --save funfix

Or you can depend on individual sub-projects, see below.

Modules: UMD and ES 2015

The library has been compiled using UMD (Universal Module Definition), so it should work with CommonJS and AMD, for standalone usage in browsers or Node.js.

But it also provides a module definition in package.json, thus providing compatibility with ECMAScript 2015 modules, for usage when used with a modern JS engine, or when bundling with a tool chain that understands ES2015 modules, like Rollup or Webpack.

Sub-projects

Funfix has been split in multiple sub-projects for à la carte dependency management. As mentioned above, you can depend on everything by depending on the funfix project.

These sub-projects are:

funfix-core

Exposes primitive interfaces and data types that need to be universally available, belonging into a standard library.

See JSDoc documentation.

Quick Overview & Usage

npm install --save funfix-core

Exposes types for expressing disjunctions:


Either	data type for expressing results with two possible outcome types (a disjoint union)
Option	data type for expressing optional values
Try	data type for representing the result of computations that may result in either success or failure

Standard interfaces and tools for dealing with universal equality and hash code generation:


IEquals	an interface for defining universal equality and hash code
is and equals	for using `IEquals` in tests, or otherwise falls back to JavaScript's equality (`==` or `valueOf()`)
hashCode	for calculating hash codes (for usage in sets and maps data structures) using `IEquals`, or otherwise falls back to calculating a hash from `.valueOf()` or from `.toString()`
isValueObject	for testing if a given object implements `IEquals`

Standard, reusable error types, that help with some common scenarios, working with error types being preferable to working with strings:


DummyError	for tagging errors used for testing purposes
IllegalArgumentError	for signaling that a given argument is violating the contract of the called function or constructor
IllegalInheritanceError	for signaling that inheriting from a certain class is illegal
IllegalStateError	for signaling that an illegal code branch was executed and thus something is wrong with the code and needs investigation (e.g. a bug)
NoSuchElementError	thrown when the user expects an element to be returned from a function call, but no such element exists
NotImplementedError	thrown in case an implementation is missing
TimeoutError	thrown in case the execution of a procedure takes longer than expected
CompositeError	for gathering multiple errors in a single reference that can expose them as a list

Misc utilities:


applyMixins	for working with mixins (i.e. classes used as interfaces, with methods that have default implementations), see Mixins for an explanation
id	is the "identity" function

funfix-exec

Contains low level / side-effectful utilities and data types for building higher level concurrency tools.

See JSDoc documentation.

Quick Overview & Usage

npm install --save funfix-exec

Scheduling tasks for asynchronous execution:


Future	a lawful, fast, cancelable alternative to JavaScript's `Promise`
Scheduler	the alternative to using `setTimeout` for asynchronous boundaries or delayed execution

In support of futures and schedulers, ICancelable data types are introduced for dealing with cancellation concerns:


ICancelable and Cancelable	for expressing actions that can be triggered to cancel processes / dispose of resources
IBoolCancelable and BoolCancelable	for cancelable references that can be queried for their `isCanceled` status
IAssignCancelable and AssignCancelable	for cancelable references that can be assigned (behave like a box for) another reference
MultiAssignCancelable	being a mutable cancelable whose underlying reference can be updated multiple times
SingleAssignCancelable	for building forward references, much like `MultiAssignCancelable` except that it can be assigned only once, triggering an error on the second attempt
SerialCancelable	being like a `MultiAssignCancelable` that cancels its previous underlying reference on updates

And also types for expressing durations:


TimeUnit	inspired by Java's own enumeration, representing time	elated units of measurement
Duration	inspired by Scala's own type, as a type safe representation for durations

funfix-effect

Defines monadic data types for controlling laziness, asynchrony and side effects. Exposes the most advanced IO implementation for JavaScript.

See JSDoc documentation.

Quick Overview & Usage

npm install --save funfix-effect

The exposed data types:


Eval	lawful, lazy, monadic data type, that can control evaluation, inspired by the `Eval` type in Typelevel Cats and by the `Coeval` type in Monix, a more simple `IO`-like type that can only handle immediate execution, no async boundaries, no error handling, not being meant for suspending side effects.
IO	lawful, lazy, monadic data type, capable of expressing and composing side effectful actions, including asynchronous, being the most potent and capable alternative to JavaScript's `Promise`, inspired by Haskell's `IO` and by the Monix Task

TypeScript or Flow?

Funfix supports both TypeScript and Flow type annotations out of the box.

It also makes the best use of the capabilities of each. For example TypeScript has bivariant generics, but Flow supports variance annotations and Funfix makes use of them. Development happens in TypeScript, due to better tooling, but both are first class citizens.

Contributing

The Funfix project welcomes contributions from anybody wishing to participate. All code or documentation that is provided must be licensed with the same license that Funfix is licensed with (Apache 2.0).

Feel free to open an issue if you notice a bug, have an idea for a feature, or have a question about the code. Pull requests are also gladly accepted. For more information, check out the contributor guide.