GraalVM 1.0.0-RC11 was released yesterday, and I thought it would be an excellent excuse to play around with it a while. I decided to create a simple Groovy script that uses Grape dependency management system to load an external library and create a standalone native image from it. I thought it wouldn’t be possible, but luckily - I was wrong.
Ignoring some of the unit tests when given conditions are not satisfied is a handy feature of a JUnit framework. I guess you have used many times constructions like
Assume.assumeNotNull(expr) in your test code. Today I would like to show you one pretty interesting corner case when the usage of
Assume.assumeNotNull(expr) throws NPE in the unit test written in Groovy.
Groovy has many useful functions built-in, and one of them is
Iterable.combinations() that takes aggregated collections and finds all combinations of items. However, if we take a look its source code, we will find out that it was implemented using very imperative approach (nested for-loops + some if-statement). In this blog post I will show you how to implement the same function using Groovy and tail-recursion algorithm. Enjoy!
Most of the object-oriented programmers prefer constructing algorithms using imperative style over using recursion. This is pretty obvious in the JVM ecosystem, where imperative iteration is much more efficient than recursive function call chain. However, what if I tell you that in Groovy you can take advantage of clean tail-recursive functions without sacrificing performance? Interested? Let’s deep dive into it.