Question

Can you explain the Apache groovy feature called, Type Inference? If I can get a definition, what it is used for, why do we need it, how to use it, etc, that would help a lot. Thank you.

Answer 1

Type inference refers to the automatic detection of the data type of an expression in a programming language. It is a feature present in some strongly statically typed languages. It is often characteristic of functional programming languages in general.

Apache Groovy is a Java-syntax-compatible object-oriented programming language for the Java platform. It is both a static and dynamic language with features similar to those of Python, Ruby, and Smalltalk. It can be used as both a programming language and a scripting language for the Java Platform, is compiled to Java virtual machine (JVM) bytecode, and interoperates seamlessly with other Java code and libraries. Groovy uses a curly-bracket syntax similar to Java's. Groovy supports closures, multiline strings, and expressions embedded in strings. Much of Groovy's power lies in its AST transformations, triggered through annotations.

Groovy 1.0 was released on January 2, 2007, and Groovy 2.0 in July 2012. Since version 2, Groovy can be compiled statically, offering type inference and performance near that of Java. Groovy 2.4 was the last major release under Pivotal Software's sponsorship which ended in March 2015. Groovy 2.5.8 is the latest stable version of Groovy. Groovy has since changed its governance structure to a Project Management Committee in the Apache Software Foundation. due to all these factors, Apache Groovy is called type inference.

Apache Groovy is a dynamic object-oriented programming language that can be used as a scripting language for the Java platform. The most prominent features are:

- Development and support: Groovy language is being constantly developed, maintained and supported

- Java compatibility: valid Java code in 99% of cases will be valid Groovy code

- Performance: starting from version 2, Groovy scripts can be statically compiled providing near Java code performance

- Additional features on top of Java that make code more readable and compact, like native support of regular expressions, XML, JSON, simplified work with files and much more
Groovy is more “modern” language

When I state “valid Java code in 99% of cases will be valid Groovy code” it means that code that is developed using Java 6, 7 or 8 will be treated as a valid Groovy code. If you are using Beanshell, for example, you are limited to Java 5 language level, which means:

- No binary literals

- No strings in “switch” statements

- No Generics (“diamond” syntax is not supported)

- No try-with-resources

- No multiple exceptions handling

Groovy has several interesting features:

● Support for static and dynamic typing: statically typed languages are those in which type checking is done at the compiling stage and not during execution. Java is a general-purpose statically typed language. Dynamic typing syntaxes such as Groovy are those in which the check is performed during execution. Python is another example. Groovy allows developers to introduce this typing within Java.

● Concise, brief, direct syntax: this allows developers that use Groovy to develop projects faster and easier.   

● Relatively short learning curve: this is a relatively simple language like Python or Ruby. It is easy for developers to learn.

● Support for unit testing: Groovy is a testing-oriented development language. In fact, it is a syntax that provides support for running tests in integrated development environments (IDEs), Ant or Maven, which are all application programming tools in Java.

● Native support for regular expressions: the Groovy syntax for creating regular expressions is really simple. This programming language has three operators for regular expressions:

-       The operator regex =~.

-       The operator match ==~.

-       The pattern operator ~String.

● The native syntax for lists and associative arrays: in programming, arrays are usually assigned to variables. These variables are often associated to data. Developers sometimes associate that information through various elements of the array through a common thread called index. That way of structuring information with programming is called an associative array.

● Native support for markup languages like XML and HTML.

● Support for domain-specific languages: a domain-specific language is a programming language or a specification dedicated to solving specific problems, through a specific technique. A general-purpose syntax such as Java, C or C++ is the opposite. Somehow it provides a general structure to solve global situations.