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   screwlisp (screwtape@mastodon.sdf.org)'s status on Thursday, 09-Jan-2025 16:48:51 JST screwlisp

   (defmacro lets ((&rest substs) &body body)
   "Did someone write let-but-its-substs already? #commonLisp #macro #programming "
   (loop
   :for body1 := body :then body2
   :for body2
   :=
   (loop
   :for new-body := body1
   :then (subst new old new-body :test 'equal)
   :for (old new) :in substs
   :finally (return new-body))
   :when (equal body1 body2)
   :return (append '(progn) body1)))

   • Embed this notice
     screwlisp (screwtape@mastodon.sdf.org)'s status on Friday, 10-Jan-2025 04:46:30 JST screwlisp

     in reply to

     • Svante

     @Ardubal that's what I thought too.

     Then I floundered with macroexpand-1 a bit, and thought maybe I just wanted a conventional macro that does substs on body. Otherwise I would have to think about the read-table

     Interestingly this means the left half doesn't have to be a symbol.

   • Embed this notice
     Svante (ardubal@mastodon.xyz)'s status on Friday, 10-Jan-2025 04:46:31 JST Svante

     in reply to

     @screwtape I am not sure, but all the use cases that I can think of here could probably be handled by macrolet and symbol-macrolet.