it would not be fun to end up compiling haskell to build your python code, because you had installed the haskell protoc backend.

Agreed, but I don’t see how this would happen. For one, the Python call site will have specified in the

HydrateSourcesRequest

the value

for_sources_types=[PythonSources]

in order to get codegen working. So, a target with HaskellSources would be ignored.