Indeed, it's a fully functional scripting language that is an extension of groovy. So "looks programmery" is more than a little reductive.

Edit: functional as in, it's not half-hearted, not functional as in functional programming.

Interesting. From the docs:

The Nextflow scripting language is an extension of the Groovy programming language. Groovy is a powerful programming language for the Java virtual machine. The Nextflow syntax has been specialized to ease the writing of computational pipelines in a declarative manner.

https://www.nextflow.io/docs/latest/script.html?highlight=gr...

Its really just a layer on top that uses the groovy DSL features

http://docs.groovy-lang.org/docs/latest/html/documentation/c...