To support a language on Heroku, you need to build your application written in that language on top of a build-time adapter that can compile the application into an executable program suitable to run on the Cedar stack. This build-time adapter is known as a buildpack in Heroku parlance. The Cedar stack provides a universal runtime into which the language support is plugged in via the buildpack. A buildpack is responsible for building a complete working runtime environment around the application. This may include language VMs and other runtime dependencies that are needed by the application. Your buildpack will need to provide these binaries and combine them with the application code.

Heroku, by default, provides buildpack support for all natively supported languages. These default buildpacks are available to all Heroku applications during compilation and are downloadable from GitHub. When you push your application to Heroku, these buildpacks are searched in order to...