MAmasak·Jan 7, 2022
Fun side note on this:
Bel's macros are definitely macros and not Kernel-style operatives. Here is a comparison, for clarity:
(A) Bel's macros do a syntax->syntax transformation, but this expansion happens (according to the spec) in the evaluator, after concluding that the operator is a macro and not a function.
(B) In the greater Lisp-and-Scheme tradition, macros do a syntax->syntax transformation, but at compile time. (Usually after "read" but before "eval".) In this sense, they are small compilers themselves. (This puts limitations on macros: they have to be "statically visible" in the code. You can't late-compute a macro at runtime in this system.)
(C) Kernel's operatives do a syntax->"side effect" transformation, at that same late stage as Bel's macros. Kernel operatives are essentially functions, except that the evaluation
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of the operands (syntax) into arguments (values) has been suppressed. In this sense, operatives are small interpreters.
If an (A) macro is well-behaved, you can often "optimize" it either to a (B) form or a (C) form. In my Bel implementation, it took me ages to notice that I could do the latter. I documented it here: https://github.com/masak/alma/issues/302#issuecomment-992556...