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macrosarc-lisp

How can I generate multiple expressions at compile time, within a macro call?

A particular macro runs each expression in its body, interleaving an atom between each expression, and collecting the results.

This works well with hard-coded expressions, but if I want to dynamically generate a series of expressions to be inserted in the body of the macro call, that won't work, obviously, because that will be evaluated after the macro has done its job.

I suppose the solution is to write my own macro to generate the expressions I need, but I'm not sure that will be evaluated before the outer macro.

I tried something like this, but it didn't work:

(mac genexpr (list)
  (map (fn (e) `(something ,e)) list))
Solution

  • Try using a begin (scheme) or progn (common lisp) form. It looks like you're using arc, which appears to name this construct do.

    (mac genexpr (list)
  `(do ,@(map (fn (c) `(something ,e)) list)))