This is the main development repository for SML/NJ and is under active development, it is not considered stable. As such, we recommend the legacy version of the system for production use cases.

This version works on AMD64 (a.k.a. x86-64) and Arm64 (a.k.a. AArch64) hardware running Linux or macOS.

• Dependencies
• Installing with Homebrew
• Building From Source
• Recompiling the System

To build the system from sources, you must have the following software installed on your machine.¹

• C++17 -- You need a C++ compiler, such as clang or gcc, that can handle C++17.

• CMake -- You need Version 3.23 or later of CMake.

• Autoconf -- Parts of the documentation and the ASDL tool require the GNU autoconf tool (version 2.71 or later).

If you use Homebrew, run the following command to get started

brew install smlnj

Dependencies are automatically installed when using this method.

Note The process for building the system from source code has changed from the legacy system.

If you want to build and install smlnj from source yourself, follow these steps:

1. Set VERSION to the version of SML/NJ that you want to build; for example

   VERSION=2025.3

2. Clone the repository

   git clone --depth 1 --branch v$VERSION --recurse-submodules https://github.com/smlnj/smlnj.git

   The --depth option limits the download to just one commit (i.e., no history), the --branch option specifies the version of the source code that you are requesting, and the --recurse-submodules option is necessary to fetch the customized version of the LLVM library that we use.

3. build the installation

   cd smlnj
   ./build.sh

   Use build.sh -h to see the list of options accepted by the build script.

   As of version 2025.1, the build.sh script will download the pre-compiled boot files if they are not present.

   As before, you can modify the config/targets file to add/remove components from the build.

After successful running of the build.sh script, bin/sml will be the interactive system.

The process of recompiling the system from source code is similar to before.

1. Switch to the system directory and run the cmb-make command:

   cd system
   ./cmb-make ../bin/sml

   The "../bin/sml" argument is optional. If omitted, the sml command in the user's PATH takes precedence. When appropriate, you can also specify a different path to an sml command.

2. Bootstrap the system

   ./makeml

3. Install the system

   ./installml -clean -boot

   The -boot option is optional. If given, the existing boot files in the root directory (e.g., boot.amd64-unix.tgz) will be replaced by the files generated by the cmb-make command (e.g., system/sml.boot.arm64-unix)

4. Rebuild the libraries and tools

   cd ..
   ./build.sh