OCaml implementation of operations in Program Algebra

Taddeus Kroes 23418c16e1 Added better error checking 11 éve
.gitignore 9340893b20 Added basic PGA parser and printer 11 éve
Makefile 9340893b20 Added basic PGA parser and printer 11 éve
parse.ml 23418c16e1 Added better error checking 11 éve
pga.ml 23418c16e1 Added better error checking 11 éve
stringify.ml 23418c16e1 Added better error checking 11 éve
types.ml 23418c16e1 Added better error checking 11 éve