Functional Programming

Functional Programming Concepts

Node JS Tutorial for Beginners #6 - Modules and require()

• What is functional programming? - 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 — Wikipedia
• What is a pure function and how do we know if something is a pure function? -It returns the same result if given the same arguments (it is also referred as deterministic). 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. So we can unit test pure functions with different contexts. Immutability: Unchanging over time or unable to be changed. Referential transparency
• What is immutability? - Unchanging over time or unable to be changed. When data is immutable, its state cannot change after it’s created.

• What is Referential transparency? - Basically, if a function consistently yields the same result for the same input, it is referentially transparent.

    pure functions + immutable data = referential transparency
  

• What is a module? - splitting one file of code into logical modules, different modules for different chunks of code that serve a different purpose. Essentially another JS file.
• What does the word ‘require’ do? - It is on the global object of node.js. It brings another module into the file you need to use it in.
• How do we bring another module into the file the we are working in? - in the file we are working in, we need to ‘require’ the file (require(./filename))…
• What do we have to do to make a module available? -…(see above) and then in the file we are requiring, we need to have a ‘module.exports=’ and assign it to the functions we want to use in our current file. Then set the require to a variable to be used where needed.

Things I want to know more about

• The examples in the Functional Programming article would not load for me, so I’d like to see some examples of pure functions at work.

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