Get into the Groovy: using Groovy to model sample sheets, input and metadata, and more

Groovy is the underlying programming language for Nextflow and can be used to model input metadata such as sample sheets. Through defining Groovy classes in the library directory, Nextflow is able to utilize these data classes to store both source and derived metadata, for example Sample Sheets, Reference data, and more. In contrast to tuples and ad-hoc inline comments, Groovy classes when used within Nextflow workflows provide a complied, typed, and concise specification of metadata and object models allowing for safer and easier-to-reason workflows.