uLisp is a version of the Lisp programming language, primarily targeting microcontrollers. See the website for more details.
You have stumbled across a reworking of the core source of uLisp. This repository contains two main components: The (mostly) C code that gets concatenated into Arduino sketches for uLisp releases, and the Common Lisp code that handles this concatenation (and some automatic code generation).
The two are in the process of being teased apart. Once that's further underway, there'll be better documentation here.
The build system is written in Common Lisp, and is being distributed as source code. Its use therefore requires an implementation of Common Lisp to be available. My main development environment is based on SBCL, but I have tried to ensure it also works on the quite portable ECL. The code is mostly portable Common Lisp, but it expects to be loaded using ASDF and therefore uses UIOP functions. As far as I can tell, all actively-developed implementations of Common Lisp provide these. In theory, any of them should work.
There is an ASDF system definition here, so one way of running the system is by
getting ASDF to find that and doing (asdf:load-system :ulisp-build). All the
code is in the ulisp-build package. It currently does weird things if that
isn't the current package, which can probably be fixed with the right printer
control variables.
There's also the file run-generator.lisp file, which configures ASDF to search
the current directory, loads the system, builds uLisp and (in ECL and ABCL)
exits. A simple shell script that loads this file in ECL is in build-all.sh.
I will readily concede that this interface is not very inviting to those who are unused to working on the command line and/or with Common Lisp. I am open to suggestions towards improving that.
uLisp's licence is fairly clear. The alterations made in this repository should be considered available under the same terms.