OCaml implementation of operations in Program Algebra

Taddeus Kroes 23418c16e1 Added better error checking 12 éve
.gitignore 9340893b20 Added basic PGA parser and printer 12 éve
Makefile 9340893b20 Added basic PGA parser and printer 12 éve
parse.ml 23418c16e1 Added better error checking 12 éve
pga.ml 23418c16e1 Added better error checking 12 éve
stringify.ml 23418c16e1 Added better error checking 12 éve
types.ml 23418c16e1 Added better error checking 12 éve