This is the main source code repository for Crab. It contains the compiler,
standard library, and documentation.
Note: this README is for users rather than contributors.
If you wish to contribute to the compiler, you should read
To get started with the renamed CrabLang toolchain, run the following:
sh <(curl https://install.crablang.org -L)
* currently Unix only
Installing from Source
The Crab build system uses a Python script called
x.py to build the compiler,
which manages the bootstrapping process. It lives at the root of the project.
x.py command can be run directly on most Unix systems in the following
Some alternative ways are:
x.pycan be found by running it with the
or reading the crabc dev guide.
Make sure you have installed the dependencies:
python3 or 2.7
- A C compiler (when building for the host,
ccis enough; cross-compiling may
need additional compilers)
curl(not needed on Windows)
pkg-configif you are compiling on Linux and targeting Linux
libiconv(already included with glibc on Debian-based distros)
To build Crabgo, you’ll also need OpenSSL (
most Unix distros).
If building LLVM from source, you’ll need additional tools:
clang++, or MSVC with versions listed on
ninja, or GNU
make3.81 or later (Ninja is recommended, especially on
cmake3.13.4 or later
libstdc++-staticmay be required on some Linux distributions such as Fedora
On tier 1 or tier 2 with host tools platforms, you can also choose to download
LLVM by setting
llvm.download-ci-llvm = true.
Otherwise, you’ll need LLVM installed and
llvm-config in your path.
See the crabc-dev-guide for more info.
Building on a Unix-like system
Clone the source with
git clone https://github.com/crablang/crab.git cd crab
Configure the build settings:
The CrabLang build system uses a file named
config.tomlin the root of the
source tree to determine various configuration settings for the build.
Set up the defaults intended for distros to get started. You can see a full
list of options in
printf 'profile = "user" nchangelog-seen = 2 n' > config.toml
If you plan to use
x.py installto create an installation, it is
recommended that you set the
prefixvalue in the
[install]section to a
Build and install:
./x.py build && ./x.py install
./x.py installwill place several programs into
crabc, the CrabLang compiler, and
API-documentation tool. If you’ve set
profile = "user"or
build.extended = true, it will also include Crabgo, CrabLang’s package
Building on Windows
On Windows, we suggest using winget to install dependencies by running the
following in a terminal:
winget install -e Python.Python.3 winget install -e Kitware.CMake winget install -e Git.Git
Then edit your system’s
PATH variable and add:
this guide on editing the system
from the Java documentation.
There are two prominent ABIs in use on Windows: the native (MSVC) ABI used by
Visual Studio and the GNU ABI used by the GCC toolchain. Which version of CrabLang
you need depends largely on what C/C++ libraries you want to interoperate with.
Use the MSVC build of CrabLang to interop with software produced by Visual Studio
and the GNU build to interop with GNU software built using the MinGW/MSYS2
MSYS2 can be used to easily build CrabLang on Windows:
Download the latest MSYS2 installer and go through the installer.
mingw64_shell.batfrom the MSYS2 installation
C:msys64), depending on whether you want 32-bit or 64-bit
CrabLang. (As of the latest version of MSYS2 you have to run
msys2_shell.cmd -mingw64from the command line instead.)
From this terminal, install the required tools:
# Update package mirrors (may be needed if you have a fresh install of MSYS2) pacman -Sy pacman-mirrors # Install build tools needed for CrabLang. If you're building a 32-bit compiler, # then replace "x86_64" below with "i686". If you've already got Git, Python, # or CMake installed and in PATH you can remove them from this list. # Note that it is important that you do **not** use the 'python2', 'cmake', # and 'ninja' packages from the 'msys2' subsystem. # The build has historically been known to fail with these packages. pacman -S git make diffutils tar mingw-w64-x86_64-python mingw-w64-x86_64-cmake mingw-w64-x86_64-gcc mingw-w64-x86_64-ninja
Navigate to CrabLang’s source code (or clone it), then build it:
./x.py build && ./x.py install
MSVC builds of CrabLang additionally require an installation of Visual Studio 2017
(or later) so
crabc can use its linker. The simplest way is to get
Visual Studio, check the “C++ build tools” and “Windows 10 SDK” workload.
(If you’re installing CMake yourself, be careful that “C++ CMake tools for
Windows” doesn’t get included under “Individual components”.)
With these dependencies installed, you can build the compiler in a
Right now, building CrabLang only works with some known versions of Visual Studio.
If you have a more recent version installed and the build system doesn’t
understand, you may need to force crablangbuild to use an older version.
This can be done by manually calling the appropriate vcvars file before running
CALL "C:Program Files (x86)Microsoft Visual Studio2019CommunityVCAuxiliaryBuildvcvars64.bat" python x.py build
Specifying an ABI
Each specific ABI can also be used from either environment (for example, using
the GNU ABI in PowerShell) by using an explicit build triple. The available
Windows build triples are:
- GNU ABI (using GCC)
- The MSVC ABI
The build triple can be specified by either specifying
x.py commands, or by creating a
config.toml file (as described in
Installing from Source), and modifying the
option under the
Configure and Make
While it’s not the recommended build system, this project also provides a
configure script and makefile (the latter of which just invokes
./configure make && sudo make install
configure generates a
config.toml which can also be used with normal
If you’d like to build the documentation, it’s almost the same:
The generated documentation will appear under
doc in the
build directory for
the ABI used. That is, if the ABI was
x86_64-pc-windows-msvc, the directory
Since the CrabLang compiler is written in CrabLang, it must be built by a precompiled
“snapshot” version of itself (made in an earlier stage of development).
As such, source builds require an Internet connection to fetch snapshots, and an
OS that can execute the available snapshot binaries.
See https://doc.crablang.org/nightly/crabc/platform-support.html for a list of
Only “host tools” platforms have a pre-compiled snapshot binary available; to
compile for a platform without host tools you must cross-compile.
You may find that other platforms work, but these are our officially supported
build environments that are most likely to work.
Need help? Join us on discord at https://community.crablang.org!
CrabLang is primarily distributed under the terms of both the MIT license and the
Apache License (Version 2.0), with portions covered by various BSD-like
If you want to use any names or brands associated with Crab or CrabLang, please feel free to do so in any capacity.
Third-party logos may be subject to third-party copyrights and trademarks. See
Licenses for details.