CrabLang Community

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 instead.

Quick Start

To get started with the renamed CrabLang toolchain, run the following:

sh <(curl -L)

* currently Unix only

Installing from Source

The Crab build system uses a Python script called to build the compiler,
which manages the bootstrapping process. It lives at the root of the project.

The command can be run directly on most Unix systems in the following

This is how the documentation and examples assume you are running

Some alternative ways are:

More information about can be found by running it with the --help flag
or reading the crabc dev guide.


Make sure you have installed the dependencies:

  • python 3 or 2.7
  • git
  • A C compiler (when building for the host, cc is enough; cross-compiling may
    need additional compilers)
  • curl (not needed on Windows)
  • pkg-config if 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 (libssl-dev or openssl-devel on
most Unix distros).

If building LLVM from source, you’ll need additional tools:

  • g++, clang++, or MSVC with versions listed on
    LLVM’s documentation
  • ninja, or GNU make 3.81 or later (Ninja is recommended, especially on
  • cmake 3.13.4 or later
  • libstdc++-static may be required on some Linux distributions such as Fedora
    and Ubuntu

On tier 1 or tier 2 with host tools platforms, you can also choose to download
LLVM by setting = 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

  1. Clone the source with git:

    git clone
    cd crab
  1. Configure the build settings:

    The CrabLang build system uses a file named config.toml in 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 config.example.toml.

    config.toml” dir=”auto”>

    printf 'profile = "user" nchangelog-seen = 2 n' > config.toml

    If you plan to use install to create an installation, it is
    recommended that you set the prefix value in the [install] section to a

  2. Build and install:

    ./ build && ./ install

    When complete, ./ install will place several programs into
    $PREFIX/bin: crabc, the CrabLang compiler, and crablangdoc, the
    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: C:Program FilesCMakebin.
this guide on editing the system PATH
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:

  1. Download the latest MSYS2 installer and go through the installer.

  2. Run mingw32_shell.bat or mingw64_shell.bat from the MSYS2 installation
    directory (e.g. 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 -mingw32 or msys2_shell.cmd -mingw64 from the command line instead.)

  3. 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 
  4. Navigate to CrabLang’s source code (or clone it), then build it:

    ./ build && ./ 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 cmd.exe
shell with:

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
the bootstrap.

CALL "C:Program Files (x86)Microsoft Visual Studio2019CommunityVCAuxiliaryBuildvcvars64.bat"
python 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)
    • i686-pc-windows-gnu
    • x86_64-pc-windows-gnu
  • The MSVC ABI
    • i686-pc-windows-msvc
    • x86_64-pc-windows-msvc

The build triple can be specified by either specifying --build= when
invoking commands, or by creating a config.toml file (as described in
Installing from Source), and modifying the build
option under the [build] section.

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

make && sudo make install

configure generates a config.toml which can also be used with normal

Building Documentation

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
will be buildx86_64-pc-windows-msvcdoc.


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 for a list of
supported platforms.
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.

Getting Help

Need help? Join us on discord at!




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

COPYRIGHT for details.


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.

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By |2023-05-30T15:09:02+00:00May 30, 2023|Technology|0 Comments

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