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People seem to use Lisp like it is some impoverished programming model. Why would I want to do things concurrently in one Lisp? Because that's how I use a Lisp

by _19qg 2y ago

People seem to use Lisp like it is some impoverished programming model. Why would I want to do things concurrently in one Lisp? Because that's how I use a Lisp system all the time. That's my normal way to do things. > But you mean a REPL as in a console-style interaction, right? I mean > 1 REPL as an example how I would use a Lisp concurrently. Yeah, I can switch between REPLs in micro seconds and run > 1 second activities in each of them. > Any command used in Emacs is an eval step in a REPL And you can't run simple Lisp code in two commands concurrently, neither in a REPL nor in a command. > `while-no-input` Type (while-no-input (dotimes (i 1000000) (print i))) in two Emacs Lisp repls and have them running concurrently. I understand that GNU Emacs can run external processes, external instances of GNU Emacs, external other Lisp systems, that it can provide some limited form of cooperative threads, ... I have lived through this stuff 30 years ago and onwards, when many Lisp implementations used cooperative threading (and some had cooperative threads deeply integrated in their Lisp code, other than GNU Emacs in 2024) and over the years switched to native preemptive threading. I also remember when we got Symmetric Multiprocessing in several Lisp systems roughly 15 years ago.

medstrom 2y ago
That'd be better as (defvar foo-i 0) (defun foo () (while-no-input (while (< foo-i 10000) (print (cl-incf foo-i)))) (when (< foo-i 10000) (run-with-idle-timer 1 nil #'foo))) Make a copy of all that, search-replacing "foo" with "bar". Run (progn (foo) (bar)). Both loops will complete eventually. EDIT: OK, you explained what you call the normal way to do things. What kind of code is this that take >1 second in each repl? Out of curosity.
- amszmidt 2y ago
  > EDIT: OK, you explained what you call the normal way to do things. What kind of code is this that take >1 second in each repl? Out of curosity. One easy example -- listing all the files under the GNU Emacs tree to index them -- you might not want to do it many times but even `find` takes a bit of time. Looping over such a list might also take a bit of time.
- lispm 2y ago
  > Both loops will complete eventually. Thanks for your effort! But I need none of this. I want to open a REPL and type (dotimes (i 1000000) (print i)) - or anything morally equivalent ;-) - and I want it to do its job and the user interface to be responsive!! There were Lisp systems, which did this 40 years ago and there are some which can do it today: Execute simple plain Lisp code concurrently without any special instrumentation. Each REPL executes by default in its own thread, concurrently. I want the same for the other tools, too. Execute (dotimes (i 1000000) (print i)) in the Emacs Lisp REPL. The UI is dead then. I find it strange that it is dead and I find it strange that there are people who don't find that strange. ;-) > What kind of code is this that take >1 second in each repl? Out of curosity. All kinds of stuff. > Out of curosity. Have you ever used a multithreaded Lisp environment as a primary work tool?

by _19qg 2y ago

medstrom 2y ago

That'd be better as (defvar foo-i 0) (defun foo () (while-no-input (while (< foo-i 10000) (print (cl-incf foo-i)))) (when (< foo-i 10000) (run-with-idle-timer 1 nil #'foo))) Make a copy of all that, search-replacing "foo" with "bar". Run (progn (foo) (bar)). Both loops will complete eventually. EDIT: OK, you explained what you call the normal way to do things. What kind of code is this that take >1 second in each repl? Out of curosity.

amszmidt 2y ago
> EDIT: OK, you explained what you call the normal way to do things. What kind of code is this that take >1 second in each repl? Out of curosity. One easy example -- listing all the files under the GNU Emacs tree to index them -- you might not want to do it many times but even `find` takes a bit of time. Looping over such a list might also take a bit of time.
lispm 2y ago
> Both loops will complete eventually. Thanks for your effort! But I need none of this. I want to open a REPL and type (dotimes (i 1000000) (print i)) - or anything morally equivalent ;-) - and I want it to do its job and the user interface to be responsive!! There were Lisp systems, which did this 40 years ago and there are some which can do it today: Execute simple plain Lisp code concurrently without any special instrumentation. Each REPL executes by default in its own thread, concurrently. I want the same for the other tools, too. Execute (dotimes (i 1000000) (print i)) in the Emacs Lisp REPL. The UI is dead then. I find it strange that it is dead and I find it strange that there are people who don't find that strange. ;-) > What kind of code is this that take >1 second in each repl? Out of curosity. All kinds of stuff. > Out of curosity. Have you ever used a multithreaded Lisp environment as a primary work tool?