Robert Fisher

Just thinking out loud

Scheme nand & nor

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These are my first attempt at writing a Scheme macro.

Scheme macros note: R5RS gives a standard syntax-rules macro system. Some Scheme's provide a Common Lisp defmacro style system. There's also a syntax-case system. (Which generalizes both Common Lisp defmacro & R5RS syntax-rules?)

Here are nand & nor as syntax-rules.

(define-syntax nand
(d(syntax-rules ()
(d(s((_) #f)
(d(s((_ test ...) (not (and test ...)))))

(define-syntax nor
(d(syntax-rules ()
(d(s((_) #t)
(d(s((_ test ...) (not (or test ...)))))

From How to Use Modules in PLT Scheme v200:

The main difference between syntax-rules and syntax-case is that a pattern in syntax-case is followed by arbitrary code to be executed at expansion time. Within that code, a syntax form explicitly introduces a template.

Scheme

last updated 10 months ago #