Compiling SED-like command in DCG phrase (update)

Hi, 

I have improved my "SED command in SWI-Prolog"  1) variables for SED expressions are  allowed.
2)  "global variables" in SED expressions are allowed.   Document in some details
should be prepared.

The following queries are real ones; outputs are edited for readability.

?- let_sed(F, w("e")/ =(`CC`)), phrase(F, `eaea`, R).
R =>  CCaCCa, 

where let_sed/2 is a run-time compiler for sed expression.

?-  F = (=(`EE`)),  phrase( F >> (w("e") / F), `eaea`, R).
R ==> EEaEEa

where term F of the sed command  of the form
     F    >>  phrase / action 
tells the sed compiler that the variables occurring on the term F are  globals.

So,  this is an error case.
?- let(F, =(`cc`)), sed(w("e")/F /* this F is local */ , `eaea`, R). 
%@ ERROR: call/2: Arguments are not sufficiently instantiated

Commands s, a, b, t, w like in unix sed commands  are defined directly based on this
in a uniform manner as a special case of our version.

?- phrase(@(s/ "e"/ "ccc"), `eaea`, R), smash(R).
R ==> cccaccca

The symbol @ indicates the expression is s, a, b, t,  w comands.

The sed compiler does a very simple `partial evaluation` on list appending 
to suppress  generating list cells. All these features have been implemented on 
my PAC library in short codes.

I am going to include these new commands to my private favorite toolbox for 
editing emacs buffer. I would like to receive responses from those 
who are doing similar things with Emacs buffer for sharing ideas.
Editing buffer with prolog  has been a  hobby for me. 
I am not expert on emacs-lisp, but I like it also.

Regards

Kuniaki Mukai