Sounds like you are looking for some ideas on implementing a transpiler. Here’s one that converts erlang to elixir - probably a little easier as they are conceptually more similar, but it might give you some ideas.
https://github.com/dazuma/erl2ex
This might also give you some ideas - lexing & parsing a bespoke language in Elixir: GitHub - fabrik42/writing_an_interpreter_in_elixir: Elixir implementation of an interpreter for the Monkey programming language · GitHub
