Vavr is essentially a functional Java library which aims to extend the features of Java8 and helps to reduce the amount of code and increase code quality.

1. Presented By: Deepak Mehra(Sr.Software Consultant)
Introduction to Vavr : A functional
Java library

2. Agenda
01
● What is Vavr?
● Prerequisite for Vavr
● Tuples
● Functions
● Values
● Collections
● Pattern Matching
● Demo

3. What is Vavr?
01
● Vavr is essentially a functional Java library which aims to extend the features of Java8 and helps to
reduce the amount of code and increase code quality.
● It provides collections, functional interfaces for error handling, concurrent programming, and
pattern matching. There are many other modules which revolves around vavr core.
● Also, It provides immutable data structures(cannot be modified once created), persistent data
structures(does preserve the previous version of itself when being modified), functional data
structures(also known as purely functional data structures), they are immutable and persistent.

4. Prerequisite for Vavr
01
● Java8
● Maven/Gradle

5. Tuples
01
You must have seen Tuples in Scala if you have ever worked on Scala. Tuple is nothing but a data
structure which will have fixed number of elements and can hold objects of heterogeneous
types(different types).

6. Functions
01
In Java8 we have Function which accepts one parameter and BiFunction which accepts two
parameters and gives output whereas vavr provides functions with upto a limit of 8 parameters.
The functional interfaces are like this Function0, Function1, Function2 and so on.

7. Values
01
● Option
● Try
● Lazy
● Either
● Future
● Collections
● Pattern Matching

8. Values
01
An expression which can be further evaluated for calculations or other. In Java, this can be
expressed by making the state of an object final and call it immutable. Vavr’s functional value
abstracts over immutable objects. If variable and objects are immutable their state is unmodifiable
and unchangeable which provides thread safety. So, we can share the variable without any fear in
a multi threaded environment.

9. Option
01
Option – We saw Option in Scala language. However, in Java something similar was introduced
with the help Optional class which behaves pretty much similar to Scala’s Option. Instances of
Option are either an instance of Some or None. Honestly speaking I don’t see much difference in
Scala’s Option and Java’s Optional.

10. Try
01
Try – Try is nothing but a container that represents a computation that may either result in an
exception or return a value. This looks similar to Either but it is different than that. Instances of Try,
are either Success or Failure

11. Lazy
01
Lazy – Lazy is a container which will represent a lazy evaluated value. Lazy is memoized already, it
evaluates only once and next time onwards returns from a cache.

12. Either
01
Either – An instance of Either is either an instance of Left or Right. A common use of Either is as an
alternative to Option for dealing with possible missing values. You can relate it Option as well, so
Left is considered to be None type and Right is considered to be Some type. Instance Right will
hold success and Left will hold failure.

13. Future
01
Future – A Future represents the result of an asynchronous computation. When the asynchronous
task is created, a future object is returned
There is a get() with Futures which will compute the result from Future but it is blocking in nature. It
also has isComplete() which returns a boolean value to mention if a future has been completed.
A future has two states: pending and completed

14. Future
01
Pending – The computation is on going. A pending future may be completed or cancelled.
Completed – The computation finished successfully with a result, failed with an exception or
cancelled.
Java8 already has a rich set of APIs for future. Future has been there since Java5 and it has
improved with time. Java8 has provided improvements to it. Now, we have
CompletableFuture(class) and CompletionStage(interface) with several callback methods.
I personally love Java8’s future API. Vavr has also introduced future class in the library with some
additional feature which we can play around with.

15. Collections
01
Collections – In vavr library a new collection library has been introduced to meet the functional
requirements, which is immutable in nature. Vavr library will essentially reduce the boilerplate code
which we will see going forward. This new collection is essentially based on java.lang.Iterable.
List in Vavr – Vavr list is essentially an immutable linked list. Mutations will result in new instances.

16. Pattern Matching
01
Pattern matching was not introduced as part of Java8, although we have worked with pattern
matching in Scala but Java never had it. Vavr library has support for pattern matching, now you can
also use pattern matching in Java8.
In pattern matching match is essentially an expression which yields some result. Also, pattern
matching is really a great feature to save a lot of time as it avoids to write if else branches and the
code looks more clean and readable.
Vavr library provides a match API which is pretty much similar to Scala’s pattern matching.

17. Pattern Matching
01
Pattern matching was not introduced as part of Java8, although we have worked with pattern
matching in Scala but Java never had it. Vavr library has support for pattern matching, now you can
also use pattern matching in Java8.
In pattern matching match is essentially an expression which yields some result. Also, pattern
matching is really a great feature to save a lot of time as it avoids to write if else branches and the
code looks more clean and readable.
Vavr library provides a match API which is pretty much similar to Scala’s pattern matching.

18. References
01
● https://www.vavr.io/vavr-docs/
● https://github.com/vavr-io/vavr
● https://blog.knoldus.com/introduction-to-vavr-a-functional-library-for-java/
● https://blog.knoldus.com/functional-java-how-to-do-pattern-matching-in-java/

19. Thank You !