Before we begin:

• Windows is not natively supported yet, but WSL should work.
• You'll need either GCC or Clang installed.

Bootstrap

Ideally, you'd pull the repo at ~/fu/, like so:

cd ~
git clone [repo] fu
cd fu

To release-build a self-verifying compiler, run:

./release-safe

This will recursively build several generations of the compiler, until you have latest-built-by-latest.

We don't "install" the compiler for you automatically - you can chose to either:

• place ~/fu/bin in your PATH;
• symlink or move ~/fu/bin/fu to a place of your liking;
• or simply ~/fu/bin/fu instead of fu to invoke the compiler:

~/fu/bin/fu

fu-0    The Fu Programming Language

        To get started:
            echo 'fn main() { println("Hello world!"); 0 }' >> hello.fu

        Build it:
            fu -b hello.fu

        Run it:
            ./hello
                Hello world!

        fu --help for more options.

Text Editor & Syntax Highlighting

Basic syntax highlighting for C or JavaScript can work for .fu files. The simpler the highlighter the better: you don't want something that will get stuck because fu code is not valid C or some such. Just use whatever works.

Compiler Development Setup

An automatic watch-rebuild-and-retest script is available at the root of the repo for compiler hackers:

cd ~/fu
fu -r watch.fu

This builds and tests several generations of the compiler, immediately and on every compiler source change, starting from a base bootstrap of a known-to-work historical compiler version.

Running this for the first time will build and run the entire test suite. This takes a while, especially on a Mac where XProtect will slow things down to a crawl. All artifacts are cached, so iteration time is excellent once this is done.

Tracking Compiler Codegen

Every run of the test suite emits all code generated + various diagnostics to testdiff/now.td. The file is big and rarely commited, but very useful when you want to compare differences in codegen between two commits.

With watch.fu running, checkout the commit prior to your change, commit the now.td you get out of the testsuite, cherry-pick your change on top and enjoy the diff of everything it affects.

Tracking Compiler Performance

A script for benchmarking compiler performance is available at the root of the repo. To compare a bunch of commits, kill watch.fu, reset --hard and run ./bench AAAAAAA BBBBBBB CCCCCCC. The script pre-builds per-commit non-self-testing release compiler executables, then runs them back to back compiling the compiler itself at the commit you started from. You'll also get rough comparisons of per-pass memory use.

Compiler Bug Auto-Reducer

TODO cleanup & describe reduce.js