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3 points by shawn 2149 days ago | link | parent

Yes, Lumen has this. https://docs.ycombinator.lol/tutorial/macros

https://imgur.com/a/CUccgz1

  (define-macro when (condition rest: body)
    `(if ,condition (do ,@body)))
  (when true
    (list 42
    (let-macro ((when (condition rest: body)
                  `(if (not ,condition) (do ,@body))))
      (when false
        21))
     (when true
       21)))
This gives a list of '(42 21 21).

If there is interest, I can port the technique to arc3.2 and let the community take it from there. We're using arc3.2 over at https://www.laarc.io

https://github.com/shawwn/arc3.2/tree/ln