gistfile1.txt

    ./stack install hprotoc
    ~/.local/bin/hprotoc ./gtfs-realtime.proto

The proto file needed to be hacked in 4 ways:
 * comment out/delete the 'syntax = "proto2";' line.
 * insert line breaks before end curly braces:

          extensions 1000 to 1999;

        }

 * remove the newline in the definition of schedule_relationship

        optional ScheduleRelationship schedule_relationship = 5 [default = SCHEDULED];

 * Added       UNKNOWN = 5; to TripDescriptor's ScheduleRelationships.