Functional Java by Example | Part 8 – More Pure Functions

This is part 8, the last instalment of the series called “Functional Java by Example”.

The example I’m evolving in each part of the series is some kind of “feed handler” which processes documents. In the last instalment we’ve seen some pattern matching, using the Vavr library, and treated failures as data too, e.g. take an alternative path and return back to the functional flow.

In this last post of the series I’m taking functions to the extreme: everything becomes a function.

Functional Java by Example | Part 7 – Treat Failures as Data Too

This is part 7 of the series called “Functional Java by Example”.

The example I’m evolving in each part of the series is some kind of “feed handler” which processes documents. We’ve already dealt with exceptional situations before, but we’re going to take care of them, more ehm,…functionally — as data.

Functional Java by Example | Part 6 – Functions as Parameters

This is part 6 of the series called “Functional Java by Example”.

The example I’m evolving in each part of the series is some kind of “feed handler” which processes documents. In previous part we tried to make our functions as pure possible by moving as much of the side-effects, such as IO, to the outside of the system.

Now we’re going to replace some of our abstractions into functions, to be passed as parameters.

Functional Java by Example | Part 5 – Move I/O to the Outside

This is part 5 of the series called “Functional Java by Example”.

In previous part we stopped mutating our documents and returned copies of the data. Now, we need to move some I/O away.

Functional Java by Example | Part 4 – Prefer Immutability

This is part 4 of the series called “Functional Java by Example”.

In previous part we talked a bit about side effects and I’d like to elaborate a bit more about how we can prevent having our data manipulated in unexpected ways by introducing immutability into our code.

Functional Java by Example | Part 3 – Don’t Use Exceptions to Control Flow

This is part 3 of the series called “Functional Java by Example”.

The example I’m evolving in each part of the series is some kind of “feed handler” which processes documents. In previous parts I started with some original code and applied some refactorings to describe “what” instead of “how”.

In order to help the code going forward, we need to get rid of the good ol’ java.lang.Exception. (disclaimer: we can’t actually get rid of it) That’s where this part comes in.

Functional Java by Example | Part 2 – Tell a Story

This is part 2 of the series called “Functional Java by Example”.

The example I’m evolving in each part of the series is some kind of “feed handler” which processes documents. In previous part I started with some original code and applied some refactorings to describe “what” instead of “how”.

In order to help the code going forward, we need to tell a story first. That’s where this part comes in.

Functional Java by Example | Part 1 – From Imperative to Declarative

Functional Programming (FP) is about avoiding reassigning variables, avoiding mutable data structures, avoiding state and favoring functions all-the-way. What can we learn from FP if we would apply functional techniques to our everyday Java code?

In this series called “Functional Java by Example” I will refactor in 8 installments an existing piece of code to see if I can reach Functional Nirvana in Java.