![Declarative not imperative
function sumOfSquares(nums) {
var i, sum = 0, squares = [];
for (i = 0; i < nums.length; i++) {
squares.push(nums[i]*nums[i]);
}
for (i = 0; i < squares.length; i++) {
sum += squares[i];
}
return sum;
}
console.log(sumOfSquares([1, 2, 3, 4, 5]));
Imperative
¡ï Not how, but what to do](https://image.slidesharecdn.com/functionalprogramming1-171121120906/85/Functional-programming-6-320.jpg)
![Declarative not imperative
function sumOfSquares2(nums) {
return nums
.map(function(num) { return num * num; })
.reduce(function(start, num) { return start + num; }, 0)
;
}
console.log(sumOfSquares([1, 2, 3, 4, 5]));
Declarative](https://image.slidesharecdn.com/functionalprogramming1-171121120906/85/Functional-programming-7-320.jpg)
![Map, an eggjampool
var names = [¡°Mary¡±, ¡°Isla¡±, ¡°Sam¡±];
var code_names = [¡°Mr. Pink¡±, ¡°Mr. Orange¡±, ¡°Mr. Blonde¡±];
for(var i in code_names) {
var randomIndex = Math.floor(Math.random() * code_names.length);
var randomValue = code_names[randomIndex];
names[i] = randomValue;
}
console.log(names);
=> ["Mr. Blonde", "Mr. Pink", "Mr. Pink"]
Iterative Approach](https://image.slidesharecdn.com/functionalprogramming1-171121120906/85/Functional-programming-10-320.jpg)
![Map, an eggjampool cont.
var names = [¡°Mary¡±, ¡°Isla¡±, ¡°Sam¡±];
var code_names = [¡°Mr. Pink¡±, ¡°Mr. Orange¡±, ¡°Mr. Blonde¡±];
names = names.map(function(item) {
var randomIndex = Math.floor(Math.random() * code_names.length);
var randomValue = code_names[randomIndex];
return randomValue;
});
console.log(names);
=> ["Mr. Orange", "Mr. Orange", "Mr. Blonde"]
Using Map](https://image.slidesharecdn.com/functionalprogramming1-171121120906/85/Functional-programming-11-320.jpg)
More Related Content
What's hot (17)
Similar to Functional programming (20)
Recently uploaded (20)
![ESET Smart Security Crack + Activation Key 2025 [Latest]](https://cdn.slidesharecdn.com/ss_thumbnails/bagc0125seedtechmaizeppt-250402180805-04ae8272-250402193656-b12a103b-thumbnail.jpg?width=560&fit=bounds)
![[Roundtable] Choreo - The AI-Native Internal Developer Platform as a Service](https://cdn.slidesharecdn.com/ss_thumbnails/choreo-deck-250328074645-511dded7-thumbnail.jpg?width=560&fit=bounds)
![Windows 8.1 Pro Activator Crack Version [April-2025]](https://cdn.slidesharecdn.com/ss_thumbnails/lecture9-250228130043-bd676d0e-250401141425-60508047-250401150607-9cd2b2bd-thumbnail.jpg?width=560&fit=bounds)
Functional programming
- 1. Functional Programming A brief, yet practical introduction
- 2. What is functional programming? ¡ñ Immutable data, first class functions, currying, mapping, reducing, pipelining, recursing¡ Software composed of pure functions ¡° ¡±
- 3. Pure Functions ¡ï A pure function is a function that has no side effects The function doesn¡¯t rely on data outside the current function, and it doesn¡¯t change data that exists outside of the current function ¡ï Given the same inputs, it will always return the same output ¡° ¡±
- 4. DO everything with functions
- 5. Avoid side effects var potato = 0; function increment() { return potato += 1; } increment(potato) { return potato + 1; } non-functional functional
- 6. Declarative not imperative function sumOfSquares(nums) { var i, sum = 0, squares = []; for (i = 0; i < nums.length; i++) { squares.push(nums[i]*nums[i]); } for (i = 0; i < squares.length; i++) { sum += squares[i]; } return sum; } console.log(sumOfSquares([1, 2, 3, 4, 5])); Imperative ¡ï Not how, but what to do
- 7. Declarative not imperative function sumOfSquares2(nums) { return nums .map(function(num) { return num * num; }) .reduce(function(start, num) { return start + num; }, 0) ; } console.log(sumOfSquares([1, 2, 3, 4, 5])); Declarative
- 8. Higher Order functions ¡ï A function that takes a function as an input or returns a function as output, or both function speakTruth(name) { return function (string) { return name + ¡° ¡± + string; }; } var truthifier = speakTruth(¡°Ed¡±); truthifier(¡°is bad at foos¡±); => ¡°Ed is bad at foos¡±
- 9. Don¡¯t iterate ¡ï Use map and reduce A Map takes a function and a collection of items. It makes a new, empty collection, runs the function on each item in the original collection, and inserts each return value into the new collection. It then returns the new collection. Map Reduce takes a function and a collection of items. It returns a value that is created by combining the items. Reduce
- 10. Map, an eggjampool var names = [¡°Mary¡±, ¡°Isla¡±, ¡°Sam¡±]; var code_names = [¡°Mr. Pink¡±, ¡°Mr. Orange¡±, ¡°Mr. Blonde¡±]; for(var i in code_names) { var randomIndex = Math.floor(Math.random() * code_names.length); var randomValue = code_names[randomIndex]; names[i] = randomValue; } console.log(names); => ["Mr. Blonde", "Mr. Pink", "Mr. Pink"] Iterative Approach
- 11. Map, an eggjampool cont. var names = [¡°Mary¡±, ¡°Isla¡±, ¡°Sam¡±]; var code_names = [¡°Mr. Pink¡±, ¡°Mr. Orange¡±, ¡°Mr. Blonde¡±]; names = names.map(function(item) { var randomIndex = Math.floor(Math.random() * code_names.length); var randomValue = code_names[randomIndex]; return randomValue; }); console.log(names); => ["Mr. Orange", "Mr. Orange", "Mr. Blonde"] Using Map
- 12. Pure Functions, an example ¡ï A pure function is a function that has no side effects var a = 0; function increment() { return a += 1; } increment(a) { return a + 1; } non-functional functional
- 13. The end