Genspio is a typed EDSL to generate shell scripts from OCaml.
The idea is to build values of type 'a Genspio.EDSL.t with the
combinators in the Genspio.EDSL module, and compile them to POSIX
shell scripts (or one-liners) with functions from the Genspio.Compile module.
The project provides two compilers. The standard compiler generates strict but complex POSIX shell expressions, which can be even treated as one-liners. The second compiler, generates much slower but simpler scripts targeting a subset of POSIX which aims at being portable to older and buggy interpreters which are still found in the wild. In addition, a few generic optimizations have been implemented, and the API gives access to a generic AST visitor (using standard OCaml objects).
The most interesting parts of the implementation of the project are actually its testing infrastructure and its documenation.
The tests aim at evaluating the portability of the generated code by running an extensive test suite with various shells and on various systems (including by providing infrastructure to try older operating systems or other architectures with Qemu).
The documentation effort has also been extensive, and includes an browser-based
experimentation environment; to try and modify the documented
examples, see type-errors, and inspect or even download the
compilation outputs. This sub-project is based on the Tyxml and react OCaml
libraries, builds with js_of_ocaml, and includes a full OCaml REPL running in
a “Web-worker.”
Bigger, proof-of-concept, examples, are also available showing that the approach can scale. These are 100% generated Github repositories which do not depend on OCaml at all, see multi-git (scripts for dealing with a few git repositories), and and cosc (script to manage long-running processes using a hidden GNU-screen session).
Genspio was developed at the Hammer Lab of Mount Sinai to help data-analysts manage their own complex deployments of idiosyncratic bioinformatics software and data artifacts on cloud or local computing infrastructure (see Secotrec).