You can use the code from these repositories to experiment, test, build, create patches, issue pull requests, etc.
https://github.com/eclipse/ceylon.formatter - Project repository hosted on GitHub.
https://github.com/eclipse/ceylon - Project repository hosted on GitHub.
https://github.com/eclipse/ceylon-sdk - Project repository hosted on GitHub.
https://github.com/eclipse/ceylon-ide-common - Project repository hosted on GitHub.
https://github.com/eclipse/ceylon-ide-eclipse - Project repository hosted on GitHub.
https://github.com/eclipse/ceylon-lang.org - Project repository hosted on GitHub.
https://github.com/eclipse/ceylon-ide-intellij - Project repository hosted on GitHub.
https://github.com/eclipse/ceylon.tool.converter.java2ceylon - Project repository hosted on GitHub.
https://github.com/eclipse/ceylon-herd - Project repository hosted on GitHub.
https://github.com/eclipse/ceylon-web-ide-backend - Project repository hosted on GitHub.