nix-find-sandbox does not behave as advertised

[chris-martin]

(defun nix-find-sandbox (path)
  "Search for a sandbox starting at PATH traversing upwards the directory tree.
If the directory contains a `shell.nix' file, the path to this
file is returned.  Otherwise if the directory contains a
`default.nix' file, the parent directory is returned."

The implementation seems to detect the presence of any file ending in .nix, not just default.nix. This is a problem for me, because I have .nix files in various directories that do not correspond to usable shells for development.

[svenkeidel]

So what do you suggest? Search only for shell.nix files or for shell.nix and default.nix files?

[chris-martin]

I can't think of a situation where I'd want it to pick anything other than shell.nix, but I could be wrong - I haven't been developing in Nix very long.

I'd also like the search to never extend beyond a Git or Projectile root. So really I think the more important thing is just to make this function customizable.

[manveru]

Maybe this can help someone, I redefined the function for my config like this:

  (defun nix-find-sandbox-file (path file)
    "Find the given FILE by walking to / starting from PATH"
    (let ((found
          (locate-dominating-file
           path (lambda (dir) (file-exists-p (concat dir (f-path-separator) file) )))))
      (and found (concat (expand-file-name found) file))))

  (defun nix-find-sandbox (path)
    "Find the closest nix-shell, prefer shell.nix but if none is found settle with default.nix"
    (and (file-exists-p path)
         (or (nix-find-sandbox-file path "shell.nix")
             (nix-find-sandbox-file path "default.nix"))))