If a function returns same value for the same argument every time, then the function is pure. That generally means that, the function cannot use any state values that could potentially change.

Functional Purity

In OOP we treat data and functions separately. In FP, they are all the same. We can create an array of functions, pass a function as argument, return a function from a method.

First Class Function

Let's say there is a function that takes three arguments. Usually, we need to be aware of all three values to call this function, right? In partial application, the three arguments are provided at different times. I could not find a decent blog that explains this well. <a href="https://en.wikipedia.org/wiki/Partial_application">Here </a>is the wikipedia page.

Partial Application

Recursion is when a function calls itself and an end condition exists in the function to stop the method call. We could talk about this in depth another day. For now, <a href="https://dzone.com/articles/functional-programming-recursion">here </a>is a good explanation.

Recursion

Remember how we assign different values to a variable through out the program? How we use setters in classes to modify the value of class variables? That is not allowed in FP. A variable once set remains unchanged. Sort of like, making all variables <code>final.</code>We usually think of variables as vessels that hold the values. The vessel can hold different values at different times. But in FP, variables are just another name for their values. Like, PI is always 3.14..Ever imagined a different value for PI? No? In the same way, every x, y in your program can now have a single value.

Immutability

This is a method where we take simple functions and combine them into a more complex function. Let's say we have two methods <code>f(x) = x * 2 //(timesTwo) </code>and <code>f(x) = x - 1 // (minusOne) </code>. And we want to compute <code>f(x) = 2x -1 </code>. You call the <code>timesTwo </code>function first. With the output of <code>timesTwo </code>, you call the <code>minusOne </code>function. How would you code this? The requirement here is that the next function takes as argument the same type that the previous function returns.

Composition

Funcational Programming is a declarative way of programming.

What Is Functional Programming

I completed a course on Functional Programming on LinkedIn Learning and here is what I want to remember from it. What is Functional Programming? Funcational…

What Is Functional Programming

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