Feature Request: Support Prolog Style op/3 User Defined Operators

[peter-wasilko]

One of my all time favorite language features is the ability to define new operators and override the definitions of existing ones.

It makes creating minimally verbose DSLs in a base language significantly easier and it is probably the next best thing to providing full support for hygienic macros. See: #153

Here are few links to discussions of the topic :

https://www.swi-prolog.org/pldoc/man?section=operators
https://www3.cs.stonybrook.edu/~sbprolog/manual1/node45.html
https://cs.union.edu/~striegnk/learn-prolog-now/html/node84.html

And Gunnar Gotshalks' "Defining Binary & Unary Operators" provides an extended treatment of the feature in a slide deck at:

https://www.eecs.yorku.ca/course_archive/2008-09/S/3401/calendar/24%20prolog%20-%20operators%20.pdf

Pereira and Shieber "Prolog and Natural-Language Analysis" (ISBN 0-937073-18-0) leans on this language feature in defining a meta-circular interpreter.

Section "5.5 Declaring Operators" in Clocksin, W.F., and Mellish C.S. "Programming in Prolog" first introduced this concept to Prolog.