reading-notes

Functional Programming

What is functional programming?
- A style of programming that treats computation as pure mathematical functions
- Does not change states or mutable data
- Results will always be the same because the parameters are defined locally, not a mutable global object
What is a pure function and how do we know if something is a pure function?
- A function is “pure” if it always returns the same result given teh same arguments and doesn’t create any observable side effects
What are the benefits of a pure function?
- Code is easier to test
- Does not change the state of an existing data source so you will always have access to the original data
What is immutability?
- The thing cannot be changed or altered
What is Referential transparency?
- pure functions + immutable data = referential transparency
- Function returns the same result for the same input

What is a module?
- Logical clumps of codes with similar, related, or specific functionality
What does the word ‘require’ do?
- Allows you to use a function in another file
How do we bring another module into the file the we are working in?
- Use require('./<file-name>') to bring in the file
- Will need to declare a variable to handle the imported function
  - let variable = require('./<filename>);
What do we have to do to make a module available?
- Within the module, you will need to export the function
- module.exports = <function-name>;
- This allows the function to be exported from the module and imported into another module for use