Re: Turing on tree-sitter

[Philip Kaludercic]

Yuan Fu <casouri@gmail.com> writes:

>> On Oct 10, 2022, at 7:52 AM, Stefan Monnier <monnier@iro.umontreal.ca> wrote:
>> 
>>>> Is there a reason we can't use a minor mode?  Something like
>>>> 
>>>>        (add-hook 'python-mode-hook #'treesit-mode)
>>>> 
>>>> or a list
>>>> 
>>>>        (add-to-list 'treesit-modes 'python-mode)
>>>> 
>>>> ?
>>> 
>>> We could, if a minor mode is justified.  When this was previously
>>> brought up, someone said the justification for a minor mode was too
>>> weak in most cases.  But maybe we should revisit that idea.
>> 
>> I think a buffer-local `treesit-mode` plus a `global-treesit-mode` would
>> make a lot of sense, from a user's perspective.  This way they don't
>> have to hunt for the name of the boolean variable that their mode
>> decided to use to control the use of treesitter: all modes use the same
>> boolean variable called `treesit-mode`.
>
> Usually users set buffer-local variables in a major mode hook, which
> runs after the major mode is loaded, no? But major modes need to know
> whether to use tree-sitter up-front.

What if the hook is a noop and the mode definition just checks if the
function is a member?  Or is there no way to re-fontify a buffer?

> I don’t think xxx-mode-use-tree-sitter would be hard to find if every
> mode uses this pattern. Though now we are discussing adding separate
> major modes which wouldn’t use this variable. I think that indeed
> could be confusing. (How do I know if xxx language uses
> xxx-mode-use-tree-sitter or a separate major mode
> xxx-tree-sitter-mode?)

I think the issue here is not so much discoverability, but consistency.
Having to a different option for every mode can get annoying and is
difficult to automate.  It is also unnecessarily decentralised.  That is
why I think that having a single list like `treesit-modes' (by whatever
name) would be nice to have.  Using the easy customisation interface
you'd represent it as a set/radio menu where you get a list of supported
languages you can tick.

>> Then again, to me a minor mode is something so cheap that the idea that
>> "justification for a minor mode was too weak" is rather hard to grasp.
>
> I don’t think there is too much problem using minor modes, but minor
> modes wouldn’t fit very well with separate major modes. IMO it would
> be weird if turning on tree-sitter-mode changes the major mode.

I don't get why a `tree-sitter-mode' should change the major mode?

> Yuan