mirror of
https://github.com/rjNemo/functional-programming-jargon
synced 2026-06-08 19:46:41 +00:00
Moved Libraries to the bottom, added auto curry, endomorphism, some example implementations of .ap and .chain, and regenerated TOC (#102)
This commit is contained in:
Jethro Larson
hemanth.hm
parent
946058d20a
commit
49a856f6b3
1 changed files with 71 additions and 22 deletions
93
readme.md
93
readme.md
|
|
@ -8,27 +8,17 @@ Examples are presented in JavaScript (ES2015). [Why JavaScript?](https://github.
|
|||
|
||||
Where applicable, this document uses terms defined in the [Fantasy Land spec](https://github.com/fantasyland/fantasy-land)
|
||||
|
||||
__Translations:__
|
||||
__Translations__
|
||||
* [Portuguese](https://github.com/alexmoreno/jargoes-programacao-funcional)
|
||||
|
||||
__Functional programming libraries and projects for JavaScript:__
|
||||
|
||||
* [ramda](https://github.com/ramda/ramda)
|
||||
* [lodash](https://github.com/lodash/lodash)
|
||||
* [underscore.js](https://github.com/jashkenas/underscore)
|
||||
* [lazy.js](https://github.com/dtao/lazy.js)
|
||||
* [maryamyriameliamurphies.js](https://github.com/sjsyrek/maryamyriameliamurphies.js)
|
||||
* [Haskell in ES6](https://github.com/casualjavascript/haskell-in-es6)
|
||||
|
||||
### Contents
|
||||
|
||||
__Table of Contents__
|
||||
<!-- RM(noparent,notop) -->
|
||||
|
||||
|
||||
* [Arity](#arity)
|
||||
* [Higher-Order Functions (HOF)](#higher-order-functions-hof)
|
||||
* [Partial Application](#partial-application)
|
||||
* [Currying](#currying)
|
||||
* [Auto Currying](#auto-currying)
|
||||
* [Function Composition](#function-composition)
|
||||
* [Purity](#purity)
|
||||
* [Side effects](#side-effects)
|
||||
|
|
@ -45,13 +35,16 @@ __Functional programming libraries and projects for JavaScript:__
|
|||
* [Lift](#lift)
|
||||
* [Referential Transparency](#referential-transparency)
|
||||
* [Equational Reasoning](#equational-reasoning)
|
||||
* [Lambda](#lambda)
|
||||
* [Lambda Calculus](#lambda-calculus)
|
||||
* [Lazy evaluation](#lazy-evaluation)
|
||||
* [Monoid](#monoid)
|
||||
* [Monad](#monad)
|
||||
* [Comonad](#comonad)
|
||||
* [Applicative Functor](#applicative-functor)
|
||||
* [Morphism](#morphism)
|
||||
* [Isomorphism](#isomorphism)
|
||||
* [Endomorphism](#endomorphism)
|
||||
* [Isomorphism](#isomorphism)
|
||||
* [Setoid](#setoid)
|
||||
* [Semigroup](#semigroup)
|
||||
* [Foldable](#foldable)
|
||||
|
|
@ -60,6 +53,7 @@ __Functional programming libraries and projects for JavaScript:__
|
|||
* [Union type](#union-type)
|
||||
* [Product type](#product-type)
|
||||
* [Option](#option)
|
||||
* [Functional Programming Libraries in JavaScript](#functional-programming-libraries-in-javascript)
|
||||
|
||||
|
||||
<!-- /RM -->
|
||||
|
|
@ -151,6 +145,24 @@ add2(10) // 12
|
|||
|
||||
```
|
||||
|
||||
## Auto Currying
|
||||
Transforming a function that takes multiple arguments into one that if given less than its correct number of arguments returns a function that takes the rest. When the function gets the correct number of arguments it is then evaluated.
|
||||
|
||||
Underscore, lodash, and ramda have a `curry` function that works this way.
|
||||
|
||||
```js
|
||||
const add = (x, y) => x + y;
|
||||
|
||||
const curriedAdd = _.curry(add);
|
||||
curreiedAdd(1, 2) // 3
|
||||
curreiedAdd(1) // (y) => 1 + y
|
||||
curreiedAdd(1)(2) // 3
|
||||
```
|
||||
|
||||
__Further reading__
|
||||
* [Favoring Curry](http://fr.umio.us/favoring-curry/)
|
||||
* [Hey Underscore, You're Doing It Wrong!](https://www.youtube.com/watch?v=m3svKOdZijA)
|
||||
|
||||
## Function Composition
|
||||
|
||||
The act of putting two functions together to form a third function where the output of one function is the input of the other.
|
||||
|
|
@ -335,12 +347,14 @@ Lifting is when you take a value and put it into an object like a [functor](#poi
|
|||
Some implementations have a function called `lift`, or `liftA2` to make it easier to run functions on functors.
|
||||
|
||||
```js
|
||||
const mult = (a, b) => a * b;
|
||||
const liftA2 = (f) => (a, b) => a.map(f).ap(b);
|
||||
|
||||
const liftedMult = lift(mult); // this function now works on functors like array
|
||||
const mult = a => b => a * b;
|
||||
|
||||
const liftedMult = liftA2(mult); // this function now works on functors like array
|
||||
|
||||
liftedMult([1, 2], [3]); // [3, 6]
|
||||
lift((a, b) => a + b)([1, 2], [3, 4]); // [4, 5, 5, 6]
|
||||
liftA2((a, b) => a + b)([1, 2], [3, 4]); // [4, 5, 5, 6]
|
||||
```
|
||||
|
||||
Lifting a one-argument function and applying it does the same thing as `map`.
|
||||
|
|
@ -464,9 +478,15 @@ compose(foo, identity) ≍ compose(identity, foo) ≍ foo
|
|||
A monad is an object with [`of`](#pointed-functor) and `chain` functions. `chain` is like [`map`](#functor) except it un-nests the resulting nested object.
|
||||
|
||||
```js
|
||||
// Implementation
|
||||
Array.prototype.chain = function(f){
|
||||
return this.reduce((acc, it) => acc.concat(f(it)), []);
|
||||
};
|
||||
|
||||
// Usage
|
||||
['cat,dog', 'fish,bird'].chain((a) => a.split(',')) // ['cat', 'dog', 'fish', 'bird']
|
||||
|
||||
//Contrast to map
|
||||
// Contrast to map
|
||||
['cat,dog', 'fish,bird'].map((a) => a.split(',')) // [['cat', 'dog'], ['fish', 'bird']]
|
||||
```
|
||||
|
||||
|
|
@ -502,16 +522,23 @@ CoIdentity(1).extend((co) => co.extract() + 1) // CoIdentity(2)
|
|||
An applicative functor is an object with an `ap` function. `ap` applies a function in the object to a value in another object of the same type.
|
||||
|
||||
```js
|
||||
// Implementation
|
||||
Array.prototype.ap = function(xs){
|
||||
return this.reduce((acc, f) => acc.concat(xs.map(f)), []);
|
||||
};
|
||||
|
||||
// Example usage
|
||||
[(a) => a + 1].ap([1]) // [2]
|
||||
```
|
||||
|
||||
This is useful if you have multiple applicative functors and you want to apply a function that takes multiple arguments to them.
|
||||
This is useful if you have two objects and you want to apply a binary function to their contents.
|
||||
|
||||
```js
|
||||
// Arrays that you want to combine
|
||||
const arg1 = [1, 2];
|
||||
const arg2 = [3, 4];
|
||||
|
||||
// function needs to be curried for this to work
|
||||
// combining function - must be curried for this to work
|
||||
const add = (x) => (y) => x + y;
|
||||
|
||||
const partiallyAppliedAdds = [add].ap(arg1); // [(y) => 1 + y, (y) => 2 + y]
|
||||
|
|
@ -527,7 +554,19 @@ partiallyAppliedAdds.ap(arg2); // [3, 4, 5, 6]
|
|||
|
||||
A transformation function.
|
||||
|
||||
## Isomorphism
|
||||
### Endomorphism
|
||||
|
||||
A function where the input type is the same as the output.
|
||||
|
||||
```js
|
||||
// uppercase :: String -> String
|
||||
const uppercase = (str) => str.toUpperCase();
|
||||
|
||||
// decrement :: Number -> Number
|
||||
const decrement = (x) => x - 1;
|
||||
```
|
||||
|
||||
### Isomorphism
|
||||
|
||||
A pair of transformations between 2 types of objects that is structural in nature and no data is lost.
|
||||
|
||||
|
|
@ -621,7 +660,7 @@ The letters `a`, `b`, `c`, `d` are used to signify that the argument can be of a
|
|||
const map = (f) => (list) => list.map(f)
|
||||
```
|
||||
|
||||
### Further reading
|
||||
__Further reading__
|
||||
* [Ramda's type signatures](https://github.com/ramda/ramda/wiki/Type-Signatures)
|
||||
* [Mostly Adaquate Guide](https://drboolean.gitbooks.io/mostly-adequate-guide/content/ch7.html#whats-your-type)
|
||||
* [What is Hindley-Milner?](http://stackoverflow.com/a/399392/22425) on Stack Overflow
|
||||
|
|
@ -707,6 +746,16 @@ getNestedPrice({item: {price: 9.99}}); // Some(9.99)
|
|||
|
||||
`Option` is also known as `Maybe`. `Some` is sometimes called `Just`. `None` is sometimes called `Nothing`.
|
||||
|
||||
## Functional Programming Libraries in JavaScript
|
||||
|
||||
* [Ramda](https://github.com/ramda/ramda)
|
||||
* [Folktale](http://folktalejs.org)
|
||||
* [lodash](https://github.com/lodash/lodash)
|
||||
* [Underscore.js](https://github.com/jashkenas/underscore)
|
||||
* [Lazy.js](https://github.com/dtao/lazy.js)
|
||||
* [maryamyriameliamurphies.js](https://github.com/sjsyrek/maryamyriameliamurphies.js)
|
||||
* [Haskell in ES6](https://github.com/casualjavascript/haskell-in-es6)
|
||||
|
||||
---
|
||||
|
||||
__P.S:__ This repo is successful due to the wonderful [contributions](https://github.com/hemanth/functional-programming-jargon/graphs/contributors)!
|
||||
|
|
|
|||
Loading…
Reference in a new issue