FitNesse can run fixtures written in other languages: .NET, Ruby, etc.
.NET:
!define COMMAND_PATTERN {%m %p}
!define TEST_RUNNER {dotnet\FitServer.exe}
!define PATH_SEPARATOR {;}
Ruby:
!define COMMAND_PATTERN {ruby -I %p ruby/bin/FitServer.rb -v}
Need to install Ruby Fit server