Why Functional Programming Matter

What issues do we concern when implementing and maintaining systems?

One of the most concern is debugging during maintenance: "this code crashed because it observed some unexpected value."

Then, it turns out that the ideas of no side effects and immutability, which functional programming promotes, can help.

Shared mutable data is the root cause

Shared mutable data are read and updated by more than one of the methods. Share mutable data structures make it harder to track changes in different parts of your program.

An immutable object is an object that can't change its state after it's instantiated so it can't be affected by the actions of a function. It would be a dream to maintain because we wouldn't have any bad surprises about some object somewhere that unexpectedly modifies a data structure.

A new thinking: Declarative programming

There are two ways thinking about implementing a system by writing a program.

- Imperative programming: has instructions that mimic the low-level vocabulary of a computer (for example, assignment, conditional branching, and loops).

- Declarative programming: you give rules saying what you want, and you expect the system to decide how to achieve it.

Functional programming = side-effect-free + declarative programming

Functional programming exemplifies the idea of declarative programming ("just say what you want, using expressions that don't interact, and for which the system can choose the implementation") and side-effect-free which is mentioned above when using immutable objects approach.

Reference

Image result for java 8 in action

Alan Mycroft and Mario Fusco, Java 8 in Action: Lambdas, Streams, and Functional-style Programming. Part 4. Beyond Java 8.

Comments

Junit - Test fails on French or German string assertion

In my previous post about building a regex to check a text without special characters but allow German and French . I met a problem that the unit test works fine on my machine using Eclipse, but it was fail when running on Jenkins' build job. Here is my test: @Test public void shouldAllowFrenchAndGermanCharacters(){ String source = "ÄäÖöÜüß áÁàÀâÂéÉèÈêÊîÎçÇ"; assertFalse(SpecialCharactersUtils.isExistSpecialCharater(source)); } Production code: public static boolean isExistNotAllowedCharacters(String source){ Pattern regex = Pattern.compile("^[a-zA-Z_0-9_ÄäÖöÜüß áÁàÀâÂéÉèÈêÊîÎçÇ]*$"); Matcher matcher = regex.matcher(source); return !matcher.matches(); } The result likes the following: Failed tests: SpecialCharactersUtilsTest.shouldAllowFrenchAndGermanCharacters:32 null A guy from stackoverflow.com says: "This is probably due to the default encoding used for your Java source files. The ö in the string literal in the J...

Gzip upload on browsers

Today, I faced a problem that I could not upload my archive file with gzip format on Firefox, even it worked on Chrome. I was using macOS. My application had a setting to whitelist accepted files. I’ve already added "application/gzip" to that list. "It’s strange!", I thought. I finally figured out that my uploaded file's type actually was "application/x-gzip" on Firefox. I also asked my colleagues to check their uploaded files on Window and Ubuntu. Hmm… they were totally different! It was "application/x-compressed" on Window, and was "application/x-compressed-tar" on Ubuntu. In fact, gzip is already standardized by IANA. There is a note in RFC-6713 as below: "Some applications have informally used media types such as application/gzip-compressed, application/gzipped, application/x-gunzip, application/x-gzip, application/x-gzip-compressed, and gzip/document to describe data compressed with gzip. The media types defin...

Java 8 - Persistent data structure

The following is a series of posts about "functional programming in Java" which is the result of my understanding by reading the book " Java 8 in Action: Lambdas, Streams, and Functional-style Programming, by Alan Mycroft and Mario Fusco ". 1. Why functional programming? 2. Functional programming in Java 8 3. Java 8 - Using Functions as Values 4. Java 8 - Persistent data structure Persistent data structure is also known as a simple technique but it's very important. Its other names are functional data structure and immutable data structure. Why is it "persistent"? Their values persist and are isolated from changes happening elsewhere. That's it! This technique is described as below: If you need a data structure to represent the result of a computation, you should make a new one and not mutable an existing data structure. Destructive updates version public static A doSomething(A a){ a.setProp1("new value"); return...

DevOps Toolchain Enhancement

Historically, our company ubitec had started with a customer project. Agile/Scrum was our proposal for working with customers. Time by time, Agile/Scrum also became our culture for software development. To be successful with this development approach, we somehow needed to have a fast release for customers (i.e. every one week). Back then, we had a build tool Jenkins which was responsible for having sprint release packages for our customers. The build job pipelines contain some steps such as gathering the artifacts, checking the code convention, running the tests, building docker images, and packaging an archived file (a zip file). The set of tools involved in a pipeline is roughly called a toolchain. It is just a part of a bigger process called the DevOps toolchain. Source: https://www.ibm.com/blogs/cloud-archive/2016/11/devops-architecture-available-on-bluemix-garage-method-site/ DevOps is a proven method that fits Agile. Today, it is even treated as a mandatory factor...

Fulfilling Your Contribution Needs

Human resource management motivation Managing human today is quite different from the industrial age which treats people as just "chickens". Rather than people now are very important to the success of an organization. People are an organization's special resource. They should be encouraged to grow to contribute their effort and creativeness to their beloved working environment because the contribution is one of their most needs in life. Training people: getting rid of the ineffective model and adopting the new one The ineffective model of training people: Hiring new people --> giving them a crash course once --> expecting them working effectively. That somehow makes sense but you're about to expect a luck because you do not really spend your effort for mentoring them. If they can work effectively, well...lucky you! Otherwise, you will blame that these people are ineffective and you let them go and hire the new ones. What a waste of time! The new effe...

vhandit

Search This Blog