Sterling is a system for defining extensible languages using inference rules.
There are several views of extensible languages in the literature. The view we use is one with a base language and independently-developed extensions to this base, and guaranteed composition of the base language and extensions.
The base language introduces a set of syntactic categories and constructors building them. It also introduces a set of semantic analyses.
Extensions can add new constructors building the syntactic categories from the base language and define the base language's semantic analyses on them. Any such new constructors are also given a projection to the base language. Extensions can also introduce new syntactic categories and constructors of them, as well as new semantic analyses. When we combine multiple extensions, these new analyses are defined on constructors from other extensions by using the definition on the projection.
A more in-depth discussion of language extension can be found in the documentation.
Sterling is written in Silver and thus requires Silver for building. Running Sterling requires Java 8 and Bash. Some extensions will require other software to use to run the compiled version of the defined language.
Once this software is installed, run
./build
in the repository root to build the Sterling system using Silver. Then run
./install
to install the sterling script. Sterling can then be run as
sterling. The install script only needs to be run once, even if
you rebuild using the build script.
Sterling has been tested on Linux, but may run on MacOS or the Windows Subsystem for Linux (WSL).
Documentation for writing languages in Sterling and running them can be found in the docs directory.
Additionally the examples directory contains a number of languages to peruse to learn about Sterling.