Fluent Functional-Composition & Pipelining API - Built with Promises. See Docs: https://fpromises.io/
npm install functional-promises
The Functional Promises library is a Fluent API supporting a specific Function Chaining technique (using composition).
> Note: FP doesn't replace or extend Promises. It uses them.
There are many names for this general pattern. Including Collection Pipeline and Promise Chain.
The emphasis here is a seamless async/sync Developer Experience.
I call this pattern a Functional River - your data is the _water_, and your functions describe its _path_ or riverbed.
* Only 400 Lines of Source & 3Kb compressed
* Easily handle Sync, Async, Events, Promises, and Callbacks.
* Familiar methods, including Array.prototype.map, [].filter(), [].find(), [].some(), etc.
* Create Monads in JavaScript (so far as they contain side-effects to a sequence of instructions).
* Point-free code is easily achieved (no temp variables).
* Higher code test coverage w/ less repetitive code in tests.
* Use the best features from multiple programming styles: a little imperative, plenty functional, a pinch of OOP, yet still resembling declarative methods!!!
#### Library Comparison
Total Lines of Code (LoC) calculated using cloc CLI utility.
LoC #'s included because a smaller surface === fewer places bugs can hide.
| Library | Main deal | Files | Lines of Code | .min.js kB
|------------------------------ |----------- |---------: |--------------: |-------------------:
| Functional Promise v1.8.1 | Sync & Async Chains | 8 | 375 | 12 Kb (3Kb compressed)
| Bluebird v3.5.1 | Promises Replacement | 38 | 5,188 | 80 Kb
| RxJS v5.5.6 | Observables Chaining | 458 | 12,266 | 150 Kb
| IxJS v2.3.4 | \[Async\]Iterable Chaining | 521 | 12,366 | 145 Kb
Admittedly IxJS/RxJS have a far larger API than FP also some behavior in RxJS/IxJS may never be added.
Currently however there is a lot of overlap with FP (plus more planned).
The table above show FP is roughly 1/30th the LOC (lines of code) in R/IxJs.FP's bundle size is about 10% the size of either RxJS/IxJS.
BluebirdJS and FP have roughly the same number of API methods, yet Bluebird has a fair bit more code.
> To be clear: Bluebird and RxJS/IxJS are amazing. Their interface/designs has been very influential on FP.
>
> Note: R/IxJS's hyper-modular design also allows for bundles to be lots smaller (though using quite different syntax, either .pipe(...) or ix/iterable/ix/add/...).
``sh`
npm install functional-promises
Use one of the following:
`js`
const FP = require('functional-promises')
// or:
import FP from 'functional-promises'
Using .map()
`js`
FP.resolve([1, 2, 3, 4, 5])
.map(x => x * 2)
.map(x => x * 2)
.then(results => {
// results === [4, 8, 12, 16, 20]
})
Handling Events
Create function chains to handle the case where promises don't fit very naturally.
For example streams & event handlers must (usually) support multiple calls over time.
Here's how FP.chain() and FP.chainEnd()/FP.listen(obj, event) help you handle this like a pro:
`jsevent
const button = document.getElementById('submitBtn')
FP.chain() // start a chain
.then(({target}) => { // destructure 'target' from the
target.textContent = 'Clicked!'
})
.listen(button, 'click') // end the repeatable chain, started at
* Thenable Methods
* Arrays
* .map(fn)
* .filter(fn)
* .find(fn)
* .findIndex(fn)
* .some(fn)
* .none(fn)
* .series(fn)
* Errors
* .catch(fn)
* .catch(filter, fn)
* Conditional
* .thenIf(fn, ifTrue, ifFalse)
* Utilities
* .tap(fn)
* .delay(msec)
* Properties
* .get(keyName)
* .set(keyName, value)
* Specialty Methods
* Helpers
* FP.resolve()
* FP.all(Object/Array)
* FP.unpack()
* Events
* .listen(obj, ...eventNames)
* Composition Pipelines
* FP.chain(options)
* .chainEnd()
* Modifiers
* .quiet() - prevents errors from stopping array methods mid-loop
* .concurrency(threadLimit) - limits parallel workers for array methods
`sh``
git clone git@github.com:functional-promises/functional-promises.git
cd functional-promises
npm install
npm test
> Thanks to several influencial projects: RxJS, IxJS, Bluebird, asynquence, FantasyLand, Gulp, HighlandJS, et al.
>
> Special thanks to Kyle Simpson, Eric Elliot, and Sarah Drasner for their work for the OSS community, as well as their advice & encouragement.