That's right @ericmo. The C# and F# Dockerfiles are derived from this Mono base image:

https://github.com/docker-exec/base-mono/blob/v1.0.0/Dockerf...

as can be seen from their respective Dockerfiles:

https://github.com/docker-exec/csharp/blob/v1.0.0/Dockerfile https://github.com/docker-exec/fsharp/blob/v1.0.0/Dockerfile

The actual execution invokes this script which calls mcs or fsharpc to compile, and then executes using the Mono runtime:

https://github.com/docker-exec/image-common/blob/v1.0.0/dexe...