This is an OCaml implementation of the 3 Counter Machine from Sec.1.3.2 of Plotkin's lecture notes on structural operational semantics [http://homepages.inf.ed.ac.uk/gdp/publications/SOS.ps].

$ make

To interpret the program tests/test5-double.3cm with input 5, just run:

$ ./main.byte -input 5 tests/test5-double.3cm 
Opening file "tests/test5-double.3cm"

Program:

  1: zero x 6 else 2
  2: dec x
  3: inc y
  4: inc y
  5: zero x 6 else 2
  6: stop

Running with input 5

Result: 10

There is also an option "-trace" to trace the execution.