phrasal-functions

Functions with chained, fluent options.

Install

npm install phrasal-functions

Usage

A quick example.

const { phrasal } = require('phrasal-functions');

const make = phrasal({
  fn: (options, ...args) => console.log(options, args),
  path: [
    { key: 'who', values: ['my', 'your'] },
    { key: 'what', values: ['day', 'hour', 'minute'] },
  ],
});

make.my.day({ party: true });
// -> { who: 'my', what: 'day' } [{ party: true }]

Features

Phrasal function

Create functions that are called like real language phrases. The phrasal options are passed to the function as its first argument.

const { phrasal } = require('phrasal-functions');

const make = phrasal({
  fn: (options, arg) => ({ ...options, ...arg, foo: 'baz' }),
  path: [
    { key: 'who', values: ['my', 'your'] },
    { key: 'what', values: ['day', 'hour', 'minute'] },
  ],
});

const result = make.my.day({ party: true });
// -> { who: 'my', what: 'day', party: true, foo: 'baz' }

Decoration (Proxy)

You can also decorate (proxy) an existing object with a phrasal function. Use proxy for that purpose with the object as first argument. The function fn will implicitly have this bound to the proxied object (unless you use an ES6 arrow function which doesn't have this by definition). To explicitly change this to another object, you may provide a bind property with the desired object.

const { proxy } = require('phrasal-functions');

const johnObj = { name: 'John' };
const john = proxy(johnObj, {
  fn: function (options, arg) {
    return { who: this.name, ...options, ...arg };
  },
  // bind: otherObj,
  path: [
    { key: 'say' },
    { key: 'what', values: ['hello', 'goodbye', 'boo'] },
  ],
});

const result = john.say.goodbye({ to: 'Joe' });
// -> { who: 'John', say: 'say', what: 'goodbye', to: 'Joe' }

{ key: 'say' } in the example above is a fix option which is a shorthand for { key: 'say', values: ['say'] }.

Dynamic options

In some cases, it is useful to create syntax elements dynamically. This can be done by providing a function to values instead of an array of strings. The function, of course, has to return an array of strings. It gets the options as collected so far and has this bound properly (unless you use an ES6 arrow function which doesn't have this by definition).

const { phrasal } = require('phrasal-functions');

const my = phrasal({
  fn: (options, ...args) => { ... },
  path: [
    { key: 'animal', values: ['dog', 'cat'] },
    { key: 'is' },
    { key: 'action',
      values: ({ animal }) =>
        (animal === 'dog' ? ['barking', 'chewing', 'playing'] : ['purring', 'playing']) },
  ],
});

my.dog.is.chewing();
my.cat.is.purring();

{ key: 'is' } in the example above is a fix option which is a shorthand for { key: 'is', values: ['is'] }.

Floating elements

A phrasal function's path elements describe a fixed syntax, i.e., all the path elements have to be provided in exactly this order when calling the phrasal function. In addition, you can specify floating elements which may occur optionally at any position (except the last) in the call of the phrasal function.

const { proxy } = require('phrasal-functions');

const john = phrasal({
  fn: function (options, arg) {
    return { ...options, ...arg };
  },
  path: [
    { key: 'say', values: ['say', 'shout', 'yell', 'scream'] },
    { key: 'what', values: ['hello', 'goodbye', 'boo'] },
  ],
  floating: [
    { key: 'not' },
  ],
});

john.say.goodbye({ to: 'Joe' });
// -> { say: 'say', what: 'goodbye', to: 'Joe' }
john.not.scream.boo({ to: 'Joe' });
// -> { not: 'not', say: 'scream', what: 'boo', to: 'Joe' }
john.yell.not.hello({ to: 'Joe' });
// -> { not: 'not', say: 'yell', what: 'hello', to: 'Joe' }

Async functions

fn can also be an async function returning a promise. Consequently, use await when calling the phrasal function:

const my = phrasal({
  fn: async () => Promise.resolve(...),
  ...
});
await my.phrasal.fun();

Multiple paths

You can also provide multiple phrasal functions at the same time. The first matching path wins, i.e., the first fragments decide which path is taken.

const { phrasal } = require('phrasal-functions');

const fn = (options, ...args) => { ... };

const my = phrasal({
  fn, // could also be an extra handler just for dogs
  path: [
    { key: 'animal', values: ['dog'] },
    { key: 'is' },
    { key: 'action', values: ['barking', 'chewing', 'playing'] },
  ],
}, {
  fn, // could also be an extra handler just for cats
  path: [
    { key: 'animal', values: ['cat'] },
    { key: 'is' },
    { key: 'action', values: ['purring', 'playing'] },
  ],
});

my.dog.is.chewing();
my.cat.is.purring();

frankthelen/phrasal-functions