The LLVM tutorial is a venerable and important part of the project's documentation. It's been there for as long as I've been using LLVM (and according to the logs, a few years before that), almost always the first resource newcomers to the project are pointed to. It strikes just the right balance between simplicity and interesting content to provide an enticing introduction to LLVM. For a motivated reader, it shouldn't take more than a work day or two to go through it from start to finish, building a full compiler for a simple but "real" programming language in the process; how cool is that?

Anyway, it occurred to me that since the "official" version of the tutorial is in C++ and the only alternative checked into the tree is in OCaml, it may be interesting to re-implement the tutorial in Python. While I wouldn't write an industrial strength compiler in Python, it's a great prototyping platform, and when thinking about compilers and languages in general, prototyping is very imporatnt. You want to try all kinds of possibilities and combinations of features quickly, to get a feel for writing code in the language before it's fully done - and Python (with LLVM) is great for that.

Enter Pykaleidoscope, a project I put on Github that follows the steps of the official LLVM tutorial, but implementing the Kaleidoscope compiler in Python, using llvmlite as the binding to LLVM.

Installing llvmlite is fairly easy - see this post if you have any issues.

While working on Pykaleidoscope, I was impressed with llvmlite's maturity and compatibility with the C++ LLVM IR APIs. I didn't run into any significant problems, except maybe lack of documentation. But documentation isn't a strong side of LLVM either, which is one of the problems the tutorial helps with. So I hope this Python version will help folks understand how to use llvmlite to build non-trivial LLVM IR in Python.


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