aloklearning/javascript-lazy-evaluation

This coding challenge solves a very interesting algorithmic problem known as Lazy Evaluation

Lazy Evaluation

• This coding challenge solves a very interesting algorithmic problem known as Lazy Evaluation. It has two ways of solving the problems, one with mutable instance, and another with immutable instance. To know more, feel free to check the following code files:
  • Mutable Evaluate Lazy
  • Immutable Evaluate Lazy
• Lazy evaluation is an evaluation strategy which delays the evaluation of an expression until its value is needed.

Built With

• JavaScript - Programming language Used to create this project
• Jest - For Unit Test Cases.

Pre-Requisites

• Have node and npm installed in your system

Running the project

• Please run npm install to first install all the dependencies to be able to successfully run the project (if you'd like to run the test and see the testcases passing based upon the conditions provided).
  • Please confirm whether you have node installed in your system by running node -v and npm -v.
• To run the file simply go inside the directory main in your terminal and do node evaluateLazy.js. Please make sure to uncomment the code in the last to see the results.
• [Optional and depenedent on the first point] To run the test simply in the root directory run this command npm run test.

Output Format

• Output will be in a format of Array of Integers with the length of the evaluate argument array provided, which is below:

[3, 5, 7];

• For successfull unit test cases running, this will be the output:

 PASS  main/evaluateLazy.test.js
  ...

Test Suites: 1 passed, 1 total
Tests:       6 passed, 6 total
Snapshots:   0 total
Time:        0.22 s, estimated 1 s
Ran all test suites.

• For failure unit test cases, this will be the output:

Lazy › returns a data when no argument is passed for inbuilt method

...

Test Suites: 1 failed, 1 total
Tests:       1 failed, 5 passed, 6 total
Snapshots:   0 total
Time:        0.31 s, estimated 1 s
Ran all test suites.

Assumptions

• target argument will always be an array and cannot be provided as number/integer to evaluate. As the statement in the project guideline mentioned it clearly: When the function is called it will be called with the remaining arguments supplied to add (if any) followed by a single argument that will be an item from the target array supplied to evaluate.

• There is no need of handling the edge cases ofr evaluate and add() args, following the documents statement: Don't be defensive about the degenerate cases (E.g. bad / missing arguments).

• [Mentioned in the problem document] add was called at least once (i.e. don't account for the case where the Lazy instance had no functions added to it).

• The add() functional arguments will always receive the integer/number constant arguments for the first nth arguments provided in the add() followed by the evaluation constant value picked from the argument target (the below code example gave the assumptions source)

add(plus(a, b) { return a + b; }, 1) // a plus function that will be given 1 as its first argument

Links

• Please goto Node to install node for your system to be able to run the app. For more information on installation of mac, do follow this link