By definition, an higher order function is a function which, at least, receives one or more other functions as arguments or returns another function as its result. In this tutorial we will focus on standard library functions as filter, map and reduce: we will see when they can be useful and how to use them.

In this tutorial you will learn:
  • What is an higher order function.
  • Why we can use higher order functions in Javascript.
  • How and when to use filter, map and reduce functions.

The arrow functions syntax was introduced with ECMAScript6: by using this new syntax, in some (but not all) cases, we can produce more concise and readable code, especially when our function contains only one expression. In this tutorial we will see how we can define an arrow function, what are the differences with standard functions and what are the cases in which the use of arrow functions is not appropriate.

In this tutorial you will learn:
  • What is an arrow function.
  • How an arrow function is defined.
  • The differences between arrow functions and standard functions.
  • The cases in which arrow functions cannot be used.

While previously available via third party libraries, promises were introduced in Javascript, as a native feature, with ECMAScript6.

They provide an alternative to callbacks when dealing with asynchronous code, providing, among the other things, a cleaner way to handle errors. In this tutorial we will see how promises work, how to create them and how to use their methods.

In this tutorial you will learn:
  • What is a Javascript promise.
  • How to create a Javascript promise.
  • How promises can be used to manage asynchronous code.
  • What are the methods that can be used with a promise.

python open function

The manipulation of files is an operation which sooner or later we'll need to perform in our programs. The python built-in open function returns a file object, which lets us interact with files in different modes: we will see them in this article.

In this python tutorial you will learn:
  • How to use the python open function.
  • What are the various modes of operation which can be used with the python open function.
  • How to interact with a file object.
  • Why is important to close a file object, and how to do it.

bash-logoBash, the Bourne Again Shell, it's the default shell on practically all major linux distributions: it is really powerful and can be also considered as a programming language, although not as sophisticated or feature-reach as python or other "proper" languages. Furthermore, the Bash scripting is a must skill for any Linux system administration job. In this tutorial we will see how to use bash arrays and perform fundamental operations on them.

After following this tutorial you should be able to understand how bash arrays work and how to perform the basic operations on them.

There are several ways on how to check what version of Java is installed on your system. Most likely the simplest way is to directly use the java binary in combination with the -version option. To do so run java -version on your terminal.
$ java -version


Our objective is to create a copy of a PostgreSQL database that is constantly synchronizing with the original one and accepts read-only queries.

Operating System and Software Versions

  • Operating system: Red Hat Enterprise Linux 7.5
  • Software: PostgreSQL server 9.2


Privileged access to both master and slave systems


Our objective is to make a dummy query execution run faster on PostgreSQL database using only the built in tools available in the database.

Operating System and Software Versions

  • Operating System: Red Hat Enterprise Linux 7.5
  • Software: PostgreSQL server 9.2


PostgreSQL server base install up and running. Access to the command line tool psql and ownership of the example database.

This tutorial covers advanced python concepts such as Python classes, constructors, encapsulation, inheritance, polymorphism and creating Python packages and modules.

Therefore, if you do not have any prior Python knowledge we refer you to our Python Fundamentals Tutorial.


The following artcile will provide you with the information on how to check Python version on your operating system.




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