Arc Forumnew | comments | leaders | submitlogin
2 points by rocketnia 64 days ago | link | parent

By the way, if you'd be interested in a version of `and` that can be used as both a Racket macro with short-circuiting behavior and a first-class procedure without it, you can do that in Racket (using essentially a symbol macro):

  (define (my-and-procedure . args)
    (andmap identity args))
  
  (define-syntax (my-and stx)
    (syntax-parse stx
      [_:id #'my-and-procedure]
      [(_ args:expr ...) #'(and args ...)]))
This basically reproduces the same halfheartedly fexpr-aware behavior as PicoLisp, but without any fexprs:

  > (map my-and (list #t #f) (list #f (displayln "oops")))
  oops
  '(#f #f)
  > (list (my-and #t #f) (my-and #f (displayln "oops")))
  '(#f #f)
In the context of Fexpress, this punning can be taken to another level, letting the first-class version of `my-and` be both a procedure and an Fexpress fexpr at the same time, while the second-class calls to it have Racket macro behavior. I've put together a test to demonstrate it:

- Code link: https://github.com/rocketnia/fexpress/blob/main/fexpress-tes...

- Code link pinned to the current commit as of this writing: https://github.com/rocketnia/fexpress/blob/e33c07a4e8252793a...

In the Fexpress proof of concept, there's no way to convert between Fexpress fexprs and Racket macros in either direction. That makes this punning pretty pointless, except perhaps as a technique for publishing libraries that can be used roughly the same way by both Racket and Fexpress programmers.