matsemann / declaraoids

Declaraoids - Declarative programming on steroids

Declaraoids-Find

• Do you think imperative programming sucks?
• Do you think functional programming isn't declarative enough?
• Do you want the computer to do your job for you?
• Then look no further!

What?

Using the power of ES6 Proxies to give you declarative programming taken too far on steroids.

Given,

var persons = [
    { name: "Mats", age: 25, sex: "M", address: { city: "Oslo"} },
    { name: "Kåre", age: 31, sex: "M", address: { city: "Bergen"} },
    { name: "Linn", age: 22, sex: "F", address: { city: "Bergen"} }
]

why do this,

var result = persons
    .filter(p => p.age > 23)
    .filter(p => p.address.city == 'Bergen')
    .map(p => ({name: p.name, gender: p.sex}));
// => [ { "name": "Kåre" , "gender": "M"} ], note the change from sex to gender

when you can do this?

var declaraoids = require('./declaraoids');
var result = declaraoids.findNameAndSexAsGenderWhereAgeGreaterThanXAndAddress_CityEqualsCity(persons, {x: 23, city: 'Bergen'});
// => [ { "name": "Kåre" , "gender": "M"} ]

Does it get more declarative than that??

Wat?^*

Proxies allow us to insert traps on objects. This trap looks at the function you try to call (which obviously doesn't exist) and then creates it dynamically using the function name.

Basically, this project allows you to call arbitrary functions, and then tries to implement those functions to do what you wanted. It only works for find, and shouldn't but could be extended to handle whatever you throw at it. In the future, us programmers won't have to think!

For other fun with proxies, see proxy-fun.

Examples

A huge example showcasing how fantastic this is

var data = [
    {
        title: "A cool article",
        author: {
            name: "Mats",
            address: {
                city: "Oslo",
                zip: "0567"
            }
        },
        content: {
            ingress: "A cool ingress",
            fullText: "A long text....",
            totalWords: 500
        }
    },
    //... and lots of others
];

var result = declaraoids.findTitleAndAuthor_NameAsAuthorWhereAuthor_Address_ZipEqualsZipAndContent_IngressIncludesXAndContent_TotalWordsGreaterThanWords(data, {zip: '0567', x: 'cool', words: 400});
assert.deepEqual(result, [{title: "A cool article", author: "Mats"}]);

Examples on usages, see test/finder.spec.js:

declaraoids.find(persons); // returns the whole array
declaraoids.findName(persons); // ["Mats", "Kåre", "Linn"]
declaraoids.findNameAndAge(persons); // [{ name: "Mats", age: 25 }, { name: "Kåre", age: 31 }, { name: "Linn", age: 22 }]

var input = { levelOne: { levelTwo: { levelThree: { levelFour: "hey"}, alsoLevelThree: "three"}}};
declaraoids.findLevelOne_LevelTwo_LevelThreeAsHelloKittyAndLevelOne_LevelTwo_AlsoLevelThreeAsShort([input]); // [{ helloKitty: { levelFour: "hey" }, short: "three" }]

declaraoids.findNameAndAgeWhereSexEqualsX(persons, {x: 'male'}); // [{ name: "Mats", age: 25 }, { name: "Kåre", age: 31 }]
declaraoids.findWhereNameEqualsX(persons, {x: "Mats"}); // [{ name: "Mats", age: 25, sex: "M", address: { city: "Oslo"}  }]
declaraoids.findWhereSexEqualsGenderAndAgeGreaterThanNr(persons, {gender: "M", nr: 30}); // { name: "Kåre", age: 30, sex: "M", address: { city: "Bergen"} }

---

Syntax

<query>: find(<selects>)(Where<conditions>)

Selects

<selects>: <select>(And<select>)*
<select>: <property>(As<name>)

• The select can be empty, it will then select the whole objects similar to select * in SQL.
• Can have multiple selects separated by And, like NameAndAge.
• Can optionally rename a select using As, like NameAsFullName
• When there is only a single select, the output is flattened

Where

<conditions>: <condition>(And<condition>)*
<condition>: <property><comparison><parameter>
<comparison>: Equals|NotEquals|LessThan|GreaterThan|Includes

• The Where is optional, will select all elements in the array if not present
• Can have multiple conditions separated by And
• A condition consists of the property to be compared, the comparison, and the name of the parameter to the function. Like NameEqualsX, will compare name on each object in the array with the value of x from the passed object.

Property

<property>: [a-zA-Z0-9_]*

• The property to select or compare.
• A normal property name, like FirstName, Address
• Underscores, _, allows arbitrary nesting. Like Address_City is a lookup on object['address']['city']
• So don't use underscores in the properties of the objects being mapped/filtered.
• Assumes properties are camelCased, so FirstName will look up object['firstName']

Arrays

You can even wrap your arrays in this, allowing you to use them as normal arrays and then tap into the power of Declaraoids-Find

var arr = arrayFinder(persons);
arr[2]; // { name: "Linn", age: 22 ....
arr.length; // 3
arr.findNameWhereAgeEqualsX({x: 25}); // ["Mats"]

Speed tests

Current results. Big overhead for small arrays, not too bad when the array grows in size. filter&map is the same logic implemented in pure JS, the results containing declaraoids are using this library.

See test/speed.spec.js for how it's tested

Result with list of 50 items
Simple filter&map x 1,231,976 ops/sec ±1.34% (88 runs sampled)
Simple declaraoids x 44,778 ops/sec ±1.07% (90 runs sampled)
Fastest is Simple filter&map

Result with list of 100000 items
Simple filter&map x 10.88 ops/sec ±1.72% (31 runs sampled)
Simple declaraoids x 7.36 ops/sec ±1.17% (23 runs sampled)
Fastest is Simple filter&map

Result with list of 50 items
Advanced filter&map x 1,093,120 ops/sec ±0.91% (91 runs sampled)
Advanced declaraoids x 36,129 ops/sec ±0.84% (88 runs sampled)
Advanced declaraoids CACHED x 63,622 ops/sec ±0.95% (90 runs sampled)
Fastest is Advanced filter&map

Result with list of 100000 items
Advanced filter&map x 17.02 ops/sec ±2.41% (46 runs sampled)
Advanced declaraoids x 8.68 ops/sec ±1.63% (26 runs sampled)
Advanced declaraoids CACHED x 9.03 ops/sec ±1.30% (27 runs sampled)
Fastest is Advanced filter&map

Future plans

Now that we have solved the find-part of your day, we will have to expand the API in other directions. Issues with ideas are welcome.

Current plans include:

• declaraoids.generateCrudApp();
• declaraoids.makeDinnerAndDoTheDishes();
• declaraoids.createDnsConfigThatDoesntRelyOnASingleProviderForMyMultiBillionDollarCompany()
• declaraoids.singularity({thisAlgorithmBecomingSkynetCost: 999999});

Should I use it?

By asking that your rights to push code to production were automagically removed.

But seriously, this is how we do it in Java-land.