The packages can be compiled with

  scalac lib.scala turing.scala abacus.scala recs.scala comp1.scala

If you get an error, it is advisable to clean 
out the existing class-files

  rm */*.class


After compilation, the examples can be run in
the REPL as well as in scala. For example


  scala ex.scala

or

  scala -cp $PWD ex.scala


The directory can be cleaned with

  rm -rf *~ lib turing abacus comp1 comp2 recs