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Get a couple books on computer programming, one on assembler and another on Basic. Get a little background relative to computers.
Macros in CNCs are not the same thing as macros in computers. That is not my point relative to getting some computer programming background. So do not look for macros in computer books.
Macros in CNCs are merely new instructions added to the basic G-code language. Macros in CNCs allow you to work with variables, do IF THEN operations, perform math and logic operations. Also DPRNT is provided.
Down load the HAAS mill manual
and study the section on Macros.