LISP macro indentation for sub-expressions?

Question

I'm using Emacs, and I have a macro that's like a switch for regexes, and runs an expression with variables bound to match results.

The indentation isn't what I'd like but I can't find if there's a way to tell the macro to indent sub-expressions.

E.g. currently usage looks like:

(regex-case "some-string"
  ("name +([a-z]+) +(.+)" (arg1 arg2)
                          (format t "~A / ~A~%" arg1 arg2))
  ("A*" ()
        (format t "all A~%")))

But I'd like the parts that run to be indented more like functions, i.e.:

(regex-case "some-string"
  ("name +([a-z]+) +(.+)" (arg1 arg2)
    (format t "~A / ~A~%" arg1 arg2))
  ("A*" ()
    (format t "all A~%")))

Is there a way to do this?

I figure a next-best thing would be to have the regex and the variables in a list, and then it naturally becomes:

(regex-case "some-string"
  (("name +([a-z]+) +(.+)" (arg1 arg2))
   (format t "~A / ~A~%" arg1 arg2))
  (("A*" ())
   (format t "all A~%")))

But I'd really like more control over it than that, if possible.

The emacs stack exchange might be better suited for this question. — Shawn
– Shawn, Commented May 30 at 20:07

phils · Accepted Answer · 2025-05-30 09:35:09Z

2

I figure that this gets close enough (nearer the desired version than the default version):

(defmacro regex-case (&rest args)
  (declare (indent defun))
  ;; ...
  )

(regex-case "some-string"
  ("name +([a-z]+) +(.+)" (arg1 arg2)
   (format t "~A / ~A~%" arg1 arg2))
  ("A*" ()
   (format t "all A~%")))

Refer to C-hig (elisp)Indenting Macros

answered May 30 at 9:35

phils

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1 Comment

myname May 30 at 20:49

Yes, declare indent is a simplest way. Indent defun should work fine for macros, but one can also use numbers if they prefer or even a function. Check info node ‘(elisp)Declare Form’ for more details.

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