Reflow is implemented in Go, but it can be used to run programs in any language.

The Reflow language (.rf files) is a DSL, the language is described in more detail here: https://github.com/grailbio/reflow/blob/master/LANGUAGE.md

If you want to work with Go, check out bigslice [1] (and bigmachine [2]), which is built on a similar architecture.

[1] https://github.com/grailbio/bigslice/ [2] https://github.com/grailbio/bigmachine