Readings: FUNCTIONAL PROGRAMMING

Functional Programming Concepts

• What is functional programming?
  “Is a programming paradigm — a style of building the structure and elements of computer programs — that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data.”

• What is a pure function and how do we know if something is a pure function? Pure function is a function that has the following properties:
  1. -Same Input- Same Output-It returns the same result if given the same arguments (it is also referred as deterministic)
  2. It does not cause any observable side effects.

• What are the benefits of a pure function?
  The code’s definitely easier to test. We don’t need to mock anything.

• What is immutability?
  When data is immutable, its state cannot change after it’s created.
  If you want to change an immutable object, you can’t. Instead, you create a new object with the new value.

• What is Referential transparency?
  pure functions + immutable data = referential transparency

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Node JS-Modules and require()

• What is a module?
  Module is just essentially another javascript file

• What does the word ‘require’ do?
  require -> need for a particular purpose.

require method is expected to:
read the content of a javascript file in a string.
evaluate that code.
save the exported function/object in a cache for later use (only read files once)

• How do we bring another module into the file the we are working in?
  use require method as this
  require('module-Path')

• What do we have to do to make a module available?
  add in the end of the module file this:
  module.export = [the part of the module that we want make it availabe outside it]