Install

Volt is built from source. The first compiler, voltc-bootstrap, is written in Rust; it builds voltc, the real compiler, which is written in Volt.

• Rust (stable) and a C compiler: cc by default, or set $CC (gcc, clang, even ccache gcc).

• LLVM 23 with its C headers, and libclang (llvm-c/ and clang-c/). voltc links libLLVM for its LLVM backend and libclang to read C layouts and C++ headers. On Arch that’s the llvm and clang packages. On Debian and Ubuntu, add LLVM’s own apt repository and install the dev packages:

  wget https://apt.llvm.org/llvm.sh && sudo bash llvm.sh 23
  sudo apt install llvm-23-dev libclang-23-dev

  voltc’s build asks llvm-config where LLVM is ($LLVM_CONFIG, else llvm-config-23, else llvm-config on your PATH), so it can live off the default paths, like Ubuntu’s /usr/lib/llvm-23.

• Optional, for the interop tests: c++ (g++ 14 or newer, or clang++, for the C++23 headers; or set $CXX), rustc and python3; and zig, go, node, a JDK 22 or later, dotnet, lua 5.4, dart, swiftc, kotlinc-native and ruby, whose tests are skipped when they’re missing.

git clone https://github.com/ChaseSunstrom/volt-bootstrap volt
cd volt
cargo build --release                        # target/release/voltc-bootstrap and bolt
cd voltc && ../target/release/bolt build --release && cd ..   # voltc/target/release/voltc

The second step is bolt building the self-hosted compiler with the bootstrap one. Put both on your PATH. Run this once, in the repository, so $PWD writes its full path into ~/.bashrc (a $PWD inside ~/.bashrc itself would be wherever the shell starts):

echo "export PATH=\"$PWD/voltc/target/release:$PWD/target/release:\$PATH\"" >> ~/.bashrc
source ~/.bashrc

voltc finds the standard library by itself: a std/ directory next to it or up to three levels above (the repository’s, from voltc/target/release/), or, for an installed toolchain, the lib/volt/std that sits beside its bin directory. $VOLT_STD or --std DIR picks another. bolt runs $VOLTC when it’s set, then a voltc next to itself or on your PATH, then voltc-bootstrap.

voltc run examples/tour.volt      # the language tour: it prints what each part does
cargo test                        # the whole suite: goldens, bolt, interop, the site's code

Next, write a first program.