bug#61051: treesit-install-language-grammar can provide the default repository URL

[Eli Zaretskii]

> Date: Wed, 25 Jan 2023 05:23:37 +0200
> From: Dmitry Gutov <dgutov@yandex.ru>
> 
> The format https://github.com/tree-sitter/tree-sitter-%s will work for a 
> lot of languages, and the user won't even have to search for the address.
> 
> The patch can look like this:
> 
> diff --git a/lisp/treesit.el b/lisp/treesit.el
> index 660039cc7cc..c1b98d085e8 100644
> --- a/lisp/treesit.el
> +++ b/lisp/treesit.el
> @@ -2708,7 +2708,8 @@ treesit--install-language-grammar-build-recipe
>         (list
>          lang
>          (read-string
> -        "Enter the URL of the Git repository of the language grammar: ")
> +        "Enter the URL of the Git repository of the language grammar: "
> +        (format "https://github.com/tree-sitter/tree-sitter-%s"; lang))
>          (empty-string-to-nil
>           (read-string
>            "Enter the tag or branch (default: default branch): "))

Sounds good, but wouldn't we confuse users in those cases where the
Tree-sitter site doesn't have a grammar?  Would it be perhaps feasible
to probe first that a Git repository at the URL exists?