Re: REPL history

[Vladimir Zhbanov <vzhbanov@gmail.com>]

On Mon, Mar 06, 2017 at 09:48:51PM +0100, Andy Wingo wrote:
> On Mon 06 Mar 2017 20:15, Vladimir Zhbanov <vzhbanov@gmail.com> writes:
> 
> > OK, put things other ways. I have a GUI app which starts REPL in
> > another thread. Is there a way to call a thunk in that REPL from
> > the GUI app? Basically, I want it to exit gracefully by calling
> > (quit) in the REPL before GUI exits. 
> 
> What if, in your GUI app, you call stop-server-and-clients! from (system
> repl server) ?  That aborts to a prompt to unwind the stack, so it's not
> catchable but a dynamic-wind out guard will run.  Only really works in
> 2.2 tho I think.

Well, I confused things, as I already said, and my first question
was incorrect. Really, I have a procedure something like the following:

(define (my-repl)
  (let ((repl (make-repl (current-language) #f))
        (history-filename (make-custom-history-filename)))
    (repl-eval repl
               `(begin
                  (use-modules (ice-9 session) ; help, apropos and such
                               (system repl command)) ; guile meta-commands
                  (display "Welcome to my REPL!\n" (current-error-port))
                  (resolve-module '(ice-9 readline))
                  ;; After resolving that module the variable
                  ;; *features* should contain 'readline.
                  (if (provided? 'readline)
                      (begin
                        (use-modules (ice-9 readline))
                        ((@ (ice-9 readline) activate-readline))
                        ((@ (ice-9 readline) read-history) ,history-filename))
                      (display "Readline is not supported in your configuration.\n")
                               (current-error-port))))
    (run-repl repl)))

So I don't use repl server here.

What I tried so far is to manually save dynamic state in repl:
  (define ds (current-dynamic-state))

and use it in GUI (with support of guile expression evaluation):
  (with-dynamic-state ds (lambda () (write-history history-filename)))

This is for readline history saving, and works pretty well.

So I was thinking to bake something like this into the above code,
probably by adding a variable on the repl-eval stage to store
initial dynamic state in repl. The problem occured when I started
to call (quit) or (throw 'quit) the same way, that is, in the
thunk called in with-dynamic-state. It just segfaulted.

And my app is tied to 2.0 these days.

-- 
  Vladimir