Merge remote-tracking branch 'hemanth/master'

package.json

@@ -0,0 +1,23 @@
+{
+  "name": "functional-programming-jargons",
+  "version": "1.0.0",
+  "description": "Jargon from the functional programming world in simple terms!",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "toc": "roadmarks"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/hemanth/functional-programming-jargon.git"
+  },
+  "author": "hemanth",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/hemanth/functional-programming-jargon/issues"
+  },
+  "homepage": "https://github.com/hemanth/functional-programming-jargon#readme",
+  "devDependencies": {
+    "roadmarks": "^1.6.3"
+  }
+}

readme.md

@@ -6,6 +6,43 @@ The goal of this document is to define jargon from functional programming in pla
 
 > Where applicable, this document uses terms defined in the [Fantasy Land spec](https://github.com/fantasyland/fantasy-land)
 
+<!-- RM(noparent,notop) -->
+
+* [Arity](#arity)
+* [Higher-Order Functions (HOF)](#higher-order-functions-hof)
+* [Partial Application](#partial-application)
+* [Currying](#currying)
+* [Composition](#composition)
+* [Purity](#purity)
+* [Side effects](#side-effects)
+* [Idempotency](#idempotency)
+* [Point-Free Style](#point-free-style)
+* [Contracts](#contracts)
+* [Guarded Functions](#guarded-functions)
+* [Categories](#categories)
+* [Value](#value)
+* [Constant](#constant)
+* [Functor](#functor)
+* [Pointed Functor](#pointed-functor)
+* [Lift](#lift)
+* [Referential Transparency](#referential-transparency)
+* [Equational Reasoning](#equational-reasoning)
+* [Lazy evaluation](#lazy-evaluation)
+* [Monoid](#monoid)
+* [Monad](#monad)
+* [Comonad](#comonad)
+* [Applicative Functor](#applicative-functor)
+* [Morphism](#morphism)
+* [Isomorphism](#isomorphism)
+* [Setoid](#setoid)
+* [Semigroup](#semigroup)
+* [Foldable](#foldable)
+* [Traversable](#traversable)
+* [Type Signatures](#type-signatures)
+
+
+<!-- /RM -->
+
 ## Arity
 
 > The number of arguments a function takes. From words like unary, binary, ternary, etc. This word has the distinction of being composed of two suffixes, "-ary" and "-ity." Addition, for example, takes two arguments, and so it is defined as a binary function or a function with an arity of two. Such a function may sometimes be called "dyadic" by people who prefer Greek roots to Latin. Likewise, a function that takes a variable number of arguments is called "variadic," whereas a binary function must be given two and only two arguments, currying and partial application notwithstanding (see below).
@@ -14,10 +51,11 @@ The goal of this document is to define jargon from functional programming in pla
 const sum = (a, b) => a + b;
 
 const arity = sum.length;
-console.log(arity);
+console.log(arity); // 2
-// => 2
+
 // The arity of sum is 2
 ```
+
 ---
 
 ## Higher-Order Functions (HOF)
@@ -26,13 +64,13 @@ console.log(arity);
 
 ```js
 const filter = (pred, xs) => {
-  const result = [];
+    const result = [];
-  for (var idx = 0; idx < xs.length; idx += 1) {
+    for (var idx = 0; idx < xs.length; idx++) {
-    if (pred(xs[idx])) {
+        if (pred(xs[idx])) {
-      result.push(xs[idx]);
+            result.push(xs[idx]);
+        }
     }
-  }
+    return result;
-  return result;
 };
 ```
 
@@ -41,7 +79,7 @@ const is = type => x => Object(x) instanceof type;
 ```
 
 ```js
-filter(is(Number), [0, '1', 2, null]); //=> [0, 2]
+filter(is(Number), [0, '1', 2, null]); // [0, 2]
 ```
 
 ## Partial Application
@@ -56,7 +94,7 @@ let sum = (a, b) => a + b;
 let partial = sum.bind(null, 40);
 
 // Invoking it with `b`
-partial(2); //=> 42
+partial(2); // 42
 ```
 
 ---
@@ -72,20 +110,17 @@ let curriedSum = (a) => (b) => a + b;
 
 curriedSum(40)(2) // 42.
 ```
+
 ---
 
-## Composition
+## Function Composition
 
-> A function which combines two values of a given type (usually also some kind of functions) into a third value of the same type.
+> The act of putting two two functions together to form a third function so that the output of one function is the input of the other.
-
-The most well-known type of composition is normal function composition.
-It allows you to combines functions that accept and return a single value.
 
 ```js
 const compose = (f, g) => a => f(g(a)) // Definition
-const floorAndToString = compose((val)=> val.toString(), Math.floor) //Usage
+const floorAndToString = compose((val) => val.toString(), Math.floor) // Usage
 floorAndToString(121.212121) // "121"
-
 ```
 
 ---
@@ -98,9 +133,9 @@ input values, and does not produce side effects.
 ```js
 let greet = "yo";
 
-greet.toUpperCase(); // YO;
+greet.toUpperCase(); // "YO"
 
-greet // yo;
+greet // "yo"
 ```
 
 As opposed to:
@@ -122,17 +157,24 @@ numbers // []
 ```js
 console.log("IO is a side effect!");
 ```
+
 ---
 
 ## Idempotent
 
 > A function is idempotent if reapplying it to its result does not produce a different result.
 
-`f(f(x)) = f(x)`
+```js
+f(f(x)) = f(x)
+```
 
-`Math.abs(Math.abs(10))`
+```js
+Math.abs(Math.abs(10))
+```
 
-`sort(sort(sort([2,1])))`
+```js
+sort(sort(sort([2,1])))
+```
 
 ---
 
@@ -143,7 +185,7 @@ console.log("IO is a side effect!");
 ```js
 // Given
 let map = fn => list => list.map(fn);
-let add = (a, b) => a + b;
+let add = a => b => a + b;
 
 // Then
 
@@ -170,7 +212,7 @@ Points-free function definitions look just like normal assignments without `func
 
 ## Categories
 
-> Objects with associated functions that adhere certain rules. E.g. [monoid](#monoid)
+> Objects with associated functions that adhere to certain rules. E.g. [Monoid](#monoid)
 
 ---
 
@@ -185,6 +227,7 @@ Object.freeze({name: 'John', age: 30}) // The `freeze` function enforces immutab
 [1]
 undefined
 ```
+
 ---
 
 ## Constant
@@ -195,13 +238,15 @@ undefined
 const five = 5
 const john = {name: 'John', age: 30}
 ```
+
 Constants are [referentially transparent](#referential-transparency). That is, they can be replaced with the values that they represent without affecting the result.
+
 In other words with the above two constants the expression:
 
 ```js
 john.age + five === ({name: 'John', age: 30}).age + (5)
-
 ```
+
 Should always return `true`.
 
 ---
@@ -213,7 +258,7 @@ Should always return `true`.
 A common functor in javascript is `Array`
 
 ```js
-[2,3,4].map( n => n * 2 ); // [4,6,8]
+[2, 3, 4].map(n => n * 2); // [4, 6, 8]
 ```
 
 Let `func` be an object implementing a `map` function, and `f`, `g` be arbitrary functions, then `func` is said to be a functor if the map function adheres to the following rules:
@@ -231,11 +276,13 @@ func.map(x => f(g(x))) == func.map(g).map(f)
 ```
 
 We can now see that `Array` is a functor because it adheres to the functor rules.
+
 ```js
 [1, 2, 3].map(x => x); // = [1, 2, 3]
 ```
 
 and
+
 ```js
 let f = x => x + 1;
 let g = x => x * 2;
@@ -243,16 +290,18 @@ let g = x => x * 2;
 [1, 2, 3].map(x => f(g(x))); // = [3, 5, 7]
 [1, 2, 3].map(g).map(f);     // = [3, 5, 7]
 ```
+
 ---
 
 ## Pointed Functor
 > A functor with an `of` function that puts _any_ single value into that functor.
 
 Array Implementation:
-```js
-  Array.prototype.of = (v) => [v];
 
-  [].of(1) // [1]
+```js
+Array.prototype.of = (v) => [v];
+
+[].of(1) // [1]
 ```
 
 ---
@@ -264,11 +313,13 @@ Array Implementation:
 Map is the same as a lift over a one-argument function:
 
 ```js
-lift(n => n * 2)([2,3,4]); // [4,6,8]
+lift(n => n * 2)([2, 3, 4]); // [4, 6, 8]
 ```
+
 Unlike map lift can be used to combine values from multiple arrays:
-```
+
-lift((a, b)  => a * b)([1, 2], [3]); // [3, 6]
+```js
+lift((a, b) => a * b)([1, 2], [3]); // [3, 6]
 ```
 
 ---
@@ -301,15 +352,17 @@ referentially transparent.
 
 ```js
 let rand = function*() {
-    while(1<2) {
+    while (1 < 2) {
         yield Math.random();
     }
 }
 ```
+
 ```js
 let randIter = rand();
-randIter.next(); // Each exectuion gives a random value, expression is evluated on need.
+randIter.next(); // Each execution gives a random value, expression is evaluated on need.
 ```
+
 ---
 
 ## Monoid
@@ -347,6 +400,7 @@ The identity value is empty array `[]`
 ```js
 [1, 2].concat([]); // [1, 2]
 ```
+
 If identity and compose functions are provided, functions themselves form a monoid:
 
 ```js
@@ -356,18 +410,17 @@ var compose = (f, g) => x => f(g(x));
 compose(foo, identity) ≍ compose(identity, foo) ≍ foo
 ```
 
-
 ---
 
 ## Monad
 
-> A monad is an object with [`of`](#pointed-functor) and `chain` functions. `Chain` is like [map](#functor) except it unnests the resulting nested object.
+> 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
-['cat,dog','fish,bird'].chain(a => a.split(',')) // ['cat','dog','fish','bird']
+['cat,dog', 'fish,bird'].chain(a => a.split(',')) // ['cat', 'dog', 'fish', 'bird']
 
 //Contrast to map
-['cat,dog','fish,bird'].map(a => a.split(',')) // [['cat','dog'], ['fish','bird']]
+['cat,dog', 'fish,bird'].map(a => a.split(',')) // [['cat', 'dog'], ['fish', 'bird']]
 ```
 
 `of` is also known as `return` in other functional languages.
@@ -388,22 +441,25 @@ let CoIdentity = v => ({
 ```
 
 Extract takes a value out of a functor.
+
 ```js
 CoIdentity(1).extract() // 1
 ```
 
-Extend runs a function on the comonad. The function should return the same type as the Comonad.
+Extend runs a function on the comonad. The function should return the same type as the comonad.
+
 ```js
 CoIdentity(1).extend(co => co.extract() + 1) // CoIdentity(2)
 ```
+
 ---
 
 ## Applicative Functor
 
-> 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.
+> 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
-[(a)=> a + 1].ap([1]) // [2]
+[(a) => a + 1].ap([1]) // [2]
 ```
 
 ---
@@ -419,6 +475,7 @@ CoIdentity(1).extend(co => co.extract() + 1) // CoIdentity(2)
 > A pair of transformations between 2 types of objects that is structural in nature and no data is lost.
 
 For example, 2D coordinates could be stored as an array `[2,3]` or object `{x: 2, y: 3}`.
+
 ```js
 // Providing functions to convert in both directions makes them isomorphic.
 const pairToCoords = (pair) => ({x: pair[0], y: pair[1]})
@@ -436,7 +493,8 @@ pairToCoords(coordsToPair({x: 1, y: 2})) // {x: 1, y: 2}
 
 > An object that has an `equals` function which can be used to compare other objects of the same type.
 
-Make array a setoid.
+Make array a setoid:
+
 ```js
 Array.prototype.equals = arr => {
     var len = this.length
@@ -459,7 +517,7 @@ Array.prototype.equals = arr => {
 
 ## Semigroup
 
-An object that has a `concat` function that combines it with another object of the same type.
+> An object that has a `concat` function that combines it with another object of the same type.
 
 ```js
 [1].concat([2]) // [1, 2]
@@ -469,7 +527,7 @@ An object that has a `concat` function that combines it with another object of t
 
 ## Foldable
 
-> An object that has a reduce function that can transform that object into some other type.
+> An object that has a `reduce` function that can transform that object into some other type.
 
 ```js
 let sum = list => list.reduce((acc, val) => acc + val, 0);
@@ -481,11 +539,13 @@ sum([1, 2, 3]) // 6
 ## Traversable
 
 ---
+
 ## Type Signatures
 
 > Often functions will include comments that indicate the types of their arguments and return types.
 
-There's quite a bit variance across the community but they often follow the following patterns:
+There's quite a bit of variance across the community but they often follow the following patterns:
+
 ```js
 // functionName :: firstArgType -> secondArgType -> returnType
 
@@ -502,8 +562,13 @@ If a function accepts another function as an argument it is wrapped in parenthes
 // call :: (a -> b) -> a -> b
 let call = f => x => f(x)
 ```
-The letters `a`, `b`, `c`, `d` are used to signify that the argument can be of any type. For this map it takes a function that transforms a value of some type `a` into another type `b`, an array of values of type `a`, and returns an array of values of type `b`.
+
+The letters `a`, `b`, `c`, `d` are used to signify that the argument can be of any type. For this `map` it takes a function that transforms a value of some type `a` into another type `b`, an array of values of type `a`, and returns an array of values of type `b`.
+
 ```js
 // map :: (a -> b) -> [a] -> [b]
-let map = f => list =>  list.map(f)
+let map = f => list => list.map(f)
 ```
+---
+
+__P.S:__ Without the wonderful [contributions](https://github.com/hemanth/functional-programming-jargon/graphs/contributors) this repo would be meaningless!