SimpleLanguage and Simple Tool
The GraalVM team has created a reference implementation of a guest language called SimpleLanguage. SimpleLanguage demonstrates the features of Truffle and explains how to use the Truffle API. A guest language developer can use SimpleLanguage as a reference. It is completely open source and is available on GitHub at https://github.com/graalvm/simplelanguage. SimpleLanguage is just a starting point and does not implement all the features.
There is also a reference implementation of Simple Tool. Simple Tool is an implementation of a code coverage tool that has been built using Truffle. This is also an open source project that can be used by tool developers to build new tools using Truffle to run on GraalVM. You can access the source code of this tool at https://github.com/graalvm/simpletool.
There is an increasing number of languages being developed with Truffle. We will be covering JavaScript, LLVM (C/C++), Ruby, Python, R, Java/Truffle, and WebAssemby...