ekytr / f.js

f.js – A *fun*ctional ECMAScript Library

f.js – A functional ECMAScript Library

Function Signatures

See docs/Function-Signatures.md

Functions

Table of contents

• Root functions

  • f.done(=Generic) -> Generic
  • f.tee(...=Fn) -> Fn -> List

• List functions

  • f.List.map(Fn, =Fn) -> Fn(List) -> Generic
  • f.List.reduce(Fn, =Generic, =Fn) -> Fn(List) -> Generic

• Object functions

  • f.Object.filterProperties(...String, =Fn) -> Fn(Object) -> Generic

---

f.done

Description

Returns firstArgument.

Signature

f.done = Fn(firstArgument: Generic) -> Generic;

---

f.tee

Description

Returns a function that;

• Applies args to callbacks.
• Returns args as a List.
• Ignores the results from callbacks.

Signature

f.tee = Fn(
    callbacks: ...Fn(args: ...Generic) -> Generic = [function(){}],
) -> Fn(args: ...Generic) -> List;

---

f.List.map

Description

Returns a function that;

• Maps input to iterator then passes the the result to callback.
• Returns the result from callback.

Signature

f.List.map = Fn(
    iterator: Fn(
        element: Generic,
        index: Int,
        array: List,
    ) -> Generic,
    callback: Fn(output: List) -> Generic = f.done,
) -> Fn(input: List) -> Generic;

Example

var addOne = function(n) { return n + 1 };
var double = function(n) { return n * 2 };

var addOneEach = f.List.map(addOne);
addOneEach([1, 2, 3]); // [2, 3, 4]

var doubleEach = f.List.map(double);
doubleEach([1, 2, 3]); // [1, 4, 6]

var addOneThenDoubleEach = f.List.map(addOne, f.List.map(double));
addOneThenDoubleEach([1, 2, 3]); // [4, 6, 8]

---

f.List.reduce

Description

Returns a function that;

• Reduces input through iterator then passes the the result to callback.
• Returns the result from callback.

Signature

f.List.reduce = Fn(
    iterator: Fn(
        previousValue: Generic,
        currentValue: Generic,
        index: Int,
        array: List,
    ) -> Generic,
    firstValue: Generic = null,
    callback: Fn(output: List) -> Generic = f.done,
) -> Fn(input: List) -> Generic;

---

f.Object.filterProperties

Description

Returns a function that;

• Deletes properties from input then passes the result to callback.
• Returns the result from callback.

Signature

f.Object.filterProperties = Fn(
    properties: ...String,
    callback: Fn(output: Object) -> Generic = f.done,
) -> Fn(input: Object) -> Generic;

Example

var removeSensitiveFields = f.Object.filterProperties('password', 'isAdmin');
Object.keys(removeSensitiveFields({
    id: 1,
    username: 'Elijah',
    password: '$2y$10$bpI4uLZfRG39MLVuWexVvuzWK2kXI1FEmFrgVVZn1FMwxeYMQoEE2',
    isAdmin: true,
    createdAt: 1422409318922,
    updatedAt: 1422409318922,
})); // ['id', 'username', 'createdAt', 'updatedAt']

Express.js + Knex.js example (http://expressjs.com/, http://knexjs.org/)

app.route('/api/users').get(function(request, response) {
    knex('Users').select().then(
        f.List.map(
            f.Object.filterProperties('password', 'isAdmin'),
            response.json
        )
    );
});