Combine multiple cdrs into one list for hooks simlification.

[hongyi-zhao]

I currently install and configure python-mode with use-package as follows:

(use-package python-mode
  :hook
  (python-mode . pyvenv-mode)
  (python-mode . try/pyvenv-workon)
  (python-mode . flycheck-mode)
  (python-mode . company-mode)
  (python-mode . yas-minor-mode))

I want to simplify the above multiple hook cons directives by combining all cdrs into one list. Are there any tips for achieving this goal with dash or similar functions/commands/macros? I've done some tries, as discussed here, but still failed to do the trick.

Regards,
HZ

[basil-conto]

Are there any tips for achieving this goal with dash or similar tools?

I don't see how Dash is relevant. use-package is a macro and you want it to be evaluated. You can always wrap it in (eval `(use-package ...) lexical-binding), and transform the contained forms to your liking, but that's not a very clean approach.

IMO use-package should be adapted to support your use-case, since it already tries to DWIM.

The next best thing, IMO, is to write your own use-package keyword (see use-package-keywords) that does what you want. I don't use use-package anymore, but IIRC this was a supported use-case.

Finally, you could write your own macro that wraps use-package, but I don't see how that would be any better than creating your own keyword or the status quo.

If you really want to convert a flat list of symbols into an alist, it's pretty simple to do in Elisp even without Dash, e.g.:

`(use-package python-mode
   :hook
   ,@(mapcar (lambda (fun) (cons 'python-mode fun))
             '( pyvenv-mode
                try/pyvenv-workon
                flycheck-mode
                company-mode
                yas-minor-mode )))

which evalutes to:

(use-package python-mode
  :hook
  (python-mode . pyvenv-mode)
  (python-mode . try/pyvenv-workon)
  (python-mode . flycheck-mode)
  (python-mode . company-mode)
  (python-mode . yas-minor-mode))

The only "benefit" you would gain from Dash is writing --map, -cut, or some zip operation instead of mapcar, lambda, and cons. Personally I wouldn't consider those any clearer in such a simple scenario.

HTH.

[yyoncho]

(-juxt 'pyvenv-mode 'try/pyvenv-workon 'flycheck-mode 'company-mode 'yas-minor-mode))

-juxt will create a function that will call the functions in the list.

[hongyi-zhao]

IMO use-package should be adapted to support your use-case, since it already tries to DWIM.

It has implemented the support of using a list in car, but not cdr.

The next best thing, IMO, is to write your own use-package keyword (see use-package-keywords) that does what you want. I don't use use-package anymore, but IIRC this was a supported use-case.

I'm still not sure what the code snippet for this method is. Any more hints?

[hongyi-zhao]

(-juxt 'pyvenv-mode 'try/pyvenv-workon 'flycheck-mode 'company-mode 'yas-minor-mode))

I tried the following:

(use-package python-mode
  :hook (python-mode . (-juxt 'pyvenv-mode 'try/pyvenv-workon 'flycheck-mode 'company-mode 'yas-minor-mode)))

But encountered the error as shown below:

Error during redisplay: (jit-lock-function 1) signaled (error "Lisp nesting exceeds ‘max-lisp-eval-depth’")
ad-real-orig-definition: Lisp nesting exceeds ‘max-lisp-eval-depth’
Can’t guess python-indent-offset, using defaults: 4 [394 times]
Error in post-command-hook (global-company-mode-check-buffers): (error "Lisp nesting exceeds ‘max-lisp-eval-depth’")
Can’t guess python-indent-offset, using defaults: 4 [393 times]
Error in delayed-warnings-hook (display-delayed-warnings): (error "Lisp nesting exceeds ‘max-lisp-eval-depth’")
Wrote /home/werner/.emacs.d/var/recentf-save.el
Package cl is deprecated
Can’t guess python-indent-offset, using defaults: 4 [394 times]
Error in post-command-hook (global-company-mode-check-buffers): (error "Lisp nesting exceeds ‘max-lisp-eval-depth’")

OTOH, I want a function which can do the job with something like the following:

(-juxt 'pyvenv-mode '(try/pyvenv-workon flycheck-mode company-mode yas-minor-mode))

or

(-juxt pyvenv-mode (try/pyvenv-workon flycheck-mode company-mode yas-minor-mode))

[basil-conto]

I'm still not sure what the code snippet for this method is. Any more hints?

I'm afraid you'll have to consult the use-package docs or look at its code for examples. IIRC you need to define a few functions with specific names to transform the keyword's arguments into the desired code.

I tried the following:

AFAICT that won't work because use-package doesn't evaluate the cdr. (python-mode . (-juxt 'foo 'bar)) is the same as (python-mode -juxt 'foo 'bar) so use-package thinks e.g. -juxt is short for -juxt-hook. If you place point after the use-package form and type M-x pp-macroexpand-last-sexp RET you can inspect what use-package is actually doing.

OTOH, I want a function which can do the job with something like the following:

Sorry, I don't understand what you mean, or how that is different to a flat list of -juxt arguments.

[hongyi-zhao]

If you place point after the use-package form and type M-x pp-macroexpand-last-sexp RET you can inspect what use-package is actually doing.

(use-package python-mode
  :hook (python-mode . (-juxt 'pyvenv-mode 'try/pyvenv-workon 'flycheck-mode 'company-mode 'yas-minor-mode)))| 

| denotes the point position. M-x pp-macroexpand-last-sexp RET gives the following:

(progn
  (straight-use-package 'python-mode)
  (defvar use-package--warning92
    #'(lambda
	(keyword err)
	(let
	    ((msg
	      (format "%s/%s: %s" 'python-mode keyword
		      (error-message-string err))))
	  (display-warning 'use-package msg :error))))
  (condition-case-unless-debug err
      (progn
	(unless
	    (fboundp 'python-mode)
	  (autoload #'python-mode "python-mode" nil t))
	(add-hook 'python-mode-hook #'python-mode)
	(add-hook '-juxt-hook #'python-mode)
	(add-hook 'quote-hook #'python-mode)
	(add-hook 'pyvenv-mode-hook #'python-mode)
	(add-hook 'quote-hook #'python-mode)
	(add-hook 'try/pyvenv-workon-hook #'python-mode)
	(add-hook 'quote-hook #'python-mode)
	(add-hook 'flycheck-mode-hook #'python-mode)
	(add-hook 'quote-hook #'python-mode)
	(add-hook 'company-mode-hook #'python-mode)
	(add-hook 'quote-hook #'python-mode)
	(add-hook 'yas-minor-mode-hook #'python-mode))
    (error
     (funcall use-package--warning92 :catch err))))

Sorry, I don't understand what you mean, or how that is different to a flat list of -juxt arguments.

I mean, let it support a more concise form without using quoting (') symbols.

[basil-conto]

M-x pp-macroexpand-last-sexp RET gives the following:

I know, I suggested using that command for your own benefit as you experiment with use-package.

I mean, let it support a more concise form without using quoting (') symbols.

You're always going to have at least one quote unless you call a macro.

[hongyi-zhao]

You're always going to have at least one quote unless you call a macro.

Do you mean use a defmacro to do the job, and then eval/call the macro?

[basil-conto]

You're always going to have at least one quote unless you call a macro.

Do you mean use a defmacro to do the job, and then eval/call the macro?

I meant that, as long as you use higher-order functions (i.e. functions that accept other functions as arguments) on named functions (i.e. function symbols like python-mode rather than anonymous lambda functions), then you will always need to quote something, because function names are symbols (e.g. #'python-mode), not variables (e.g. python-mode). Even a list of function symbols (e.g. '(python-mode)) needs to be quoted against evaluation.

The only way to refer to named functions as if they were variables is to use some sort of macro, because macro arguments are unevaluated forms.

Personally, I would rather write (-juxt #'foo #'bar #'baz) than (some-cool-macro foo bar baz). In the first case there are no surprises and the intent is clear: -juxt is a function that will evaluate all its arguments just once, and the arguments are function symbols. In the second case the symbols could be anything, and it is not immediately clear what some-cool-macro does with those symbols. The general convention is to always prefer functions over macros except when macros provide a very clear advantage in syntax and convenience. I don't think this is one of those cases, but beauty lies in the eye of the beholder ;).