Alain MELLAN <alain.mellan@st.com> wrote:
+---------------
| guile> (go)
| code before abort
| ; Aborting...
| ERROR: In procedure primitive-load in expression (primitive-load name):
| ERROR: Wrong type argument in position 1: #<closed: file 0>
| ABORT: (wrong-type-arg)
+---------------

Aha! It gets more interesting! When I tried it in SCM 4e1 (and in MzScheme),
I had *pasted* the code you gave into the top-level REPL, and it worked fine.
But when I put it in a file and "load" it, I get a similar error message to
yours:

	% scm
	...chatter...
	> (load "abort.scm")
	#<unspecified>
	> (go)
	code before abort
	; Aborting...

	ERROR: read: Wrong type in arg1 #<input-port closed>
	> 

And indeed, I got the same error from MzScheme, when using the "load":

	> (load "abort.scm")
	> (go)
	code before abort
	; Aborting...
	#<primitive:get-port-char>: input port is closed
	> 

It would appear that the continuation that gets captured during a "load"
also captures the port that is being used to "read" the loading file
(which, in retrospect, sort of makes sense, since a "load" is a kind of
"with-input-with-file"), and thus any attempt to restart that continuation
after the "load" finishes will fail.

However, if you change the initialization of the global variable "*abort*"
in the file from:

	(define *abort* '())
	(call/cc (lambda (cont) (set! *abort* cont)))
to:
	(define *abort* '())
	(define (init-abort)
	  (call/cc (lambda (cont) (set! *abort* cont))))

and then call "init-abort" from the top-level REPL, *not* during the "load",
then it all works (in both SCM 4e1 and Mzscheme, and I suspect Guile as well),
and you can re-use the continuation multiple times:

	> (load "abort.scm")
	> (init-abort)
	> (go)
	code before abort
	; Aborting...
	#f
	> (go)
	code before abort
	; Aborting...
	#f
	> 

Aren't continuations "fun"?

+---------------
| With SCM, that gives:
| ==> (go)
| code before abort
| ; Aborting...
|  
| ERROR: segment violation
+---------------

As someone else wrote, that could be a problem with CHEAP-CONTINUATIONS...


-Rob

-----
Rob Warnock, 7L-551		rpw3@sgi.com   http://reality.sgi.com/rpw3/
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