In addition, type checking is handy in languages which support Hindlely-Milner type systems (such as F# and OCaml), but python has support for optional types and so I’ll also be making sure to make use of them here. You want to avoid side effects because these can make functions difficult to test and potentially result in unpredictable behavior if a value changes when it isn’t supposed to.Ī second important concept of functional programming is immutability, and so care must be taken to avoid reassigning variables and treat them as bindings instead.

Given the same inputs, a pure function should always return a value and never modify state through the use of class attributes. It is a declarative programming paradigm in which function definitions are trees of expressions that map values to other values, rather than a sequence of imperative statements which update the running state of the program.” What does that mean for the average developer who’s used to the more common object oriented programming model (OOP)?įirstly, programs are made “by applying and composing functions”, so in our slot machine, we’ll need to make sure that we use as many pure functions as possible, a concept known as referential transparency. Jackpot! Number of spins to hit the jackpot: 562 Number of two of a kinds hit: 82 The Basics of Functional ProgrammingĪccording to Wikipedia, “Functional programming is a programming paradigm where programs are constructed by applying and composing functions. When the program is run, the output looks like this: You can view the full gist here, but I’ll also explain some of the logic used when developing from a functional perspective.

Since this involves Python, as a way to brush up on my Python I decided to build a simple, single reel slot machine using a functional programming paradigm. Recently I’ve been helping a friend with some Flask apps.

Slot machine programming app