Since Groovy 1.8.3 Groovy has an implies() method for Boolean types. Groovy 5 adds an operator ==> for this method so you have a shorter way to express a logical implication. A logical implication is a logical function that can be expressed as P ==> Q. You can read this as P implies Q or if P than Q. This expression is true in every case except when P is true, but Q is false. The following truth table shows the interpretaton of the logical implication operator:

Groovy 5 adds support for using an index variable in a for-in loop. You must define an extra variable as first argument of the for loop. This variable will be used as index variable. For each iteration of the code in the for-in loop the value of this index variable is incremented by 1. You can use this value in the for loop.

Groovy 5 adds a new utility method to create an ascii bar chart. You can use the bar method in the org.codehaus.groovy.util.StringUtil class. You can pass a value, a minimum and maximum value and optinally specify the width of the bar chart. The result is a String value consisting of a number of "blocks". A block could be whole, but also 1/8 eights of the block are used to get a nice looking bar chart. How many of these values are needed is based on the input arguments. With this method you have a nice way to format number values on a command-line.

Protobuf provides an easier and more performant approach to serialising and deserialising data. These performance capabilities and the ability to provide a common schema for data transfer objects, coupled with a performant message brokering service such as Kafka seems to be a match made in heaven.

Groovy is known for exending standard Java classes with extra methods or extra arguments for existing methods. Since Groovy 5 you can use a range as argument for the List.subList method. The range is used to determine the begin and end index of the original List instance to return.