# Functional Programming Jargons

> The whole idea of this repos is to try and define jargons from combinatorics and category theory jargons that are used in functional programming in a easier fashion.

__Let's try and define these with examples, this is a WIP please feel free to send PR ;)__


## Arity

> The number of arguments a function takes.

```js
const sum = (a, b) => a + b;

const arity = sum.length;
console.log(arity);
// => 2
// The arity of sum is 2
```
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## Partial Application

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## Currying

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## Purity

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## Side effects

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## Idempotency

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## Referential Transparency

> An expression that can be replaced with its value without changing the
behaviour of the program is said to be referential transparent.

Say we have function greet:

```js
let greet = () => "Hello World!";
```

Any invocation of `greet()` can be replaced with `Hello World!` hence greet is
referential transparent.

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## Monoid

- - -

## Monad

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## Functor
> Structure that can be mapped over.

Simplest functor in javascript is an `Array`

```js
[2,3,4].map( function(n) {
  return n + 2;
}); // [4,6,8]
```

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## Applicative Functor

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## Morphism

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