🚀 go-pugleaf

>if I had a ruleset that would convert A!B!C@D to A!B!D!C
>I think things would work better.

Without judging whether this is the right thing to do, here is a
sequence of rules to make that transformation.  I assume there may be
more than two !s in the input, and also that there are no bracketing
angle brackets present when these rules are invoked.  Oh, and I also
assume that any of A, B, ... may consist of multiple "words".

R$+!$+@$+		$:$1!<$2@$3>		focus on at-sign
R$+<$+!$+@$+>		$1$2!<$3@$4>		get all bangs outside
R$+<$+@$+>		$1$3!$2			convert at-sign to bang

Exercises for those still learning the cf language:
1. Why is the second rule needed?
2. Why is the "$:" needed in the first rule?  Why not in the third?


In case, as Steve DeJarnett suggested, you really want to turn A!B!C@D
into D!A!B!C (although RFC822 has little or nothing to do with this), a
single rule suffices.

R$+!$+@$+		$3!$1!$2		final at-sign to initial bang


Any of these rules could have undesired effects when the input is not of
the assumed form ... for instance, if there are multiple @s.
________________________________________________________
Matt Crawford	     		matt@oddjob.uchicago.edu