Apache Groovy's original use case was scripting, so there's many features like that which makes Groovy be Bash for the JVM. It was based on Beanshell originally

Apache Groovy's original use case was scripting, so there's many features like that which makes Groovy be Bash for the JVM. It was based on Beanshell originally, but with closures and collections syntax added. Just don't try building any actual systems with Groovy -- do that in a language designed from the ground up for performance, e.g. Java, Scala, or Kotlin.