Because instead of distributing two files (channels.scm and manifest.scm, or flake.lock and flake.nix), you have to execute monstruosities like `guix shell --container -m ./manifest.scm -- bash -c 'GUIX_LOCPATH=$GUIX_ENVIRONMENT/lib/locale LC_ALL=fr_FR.utf-8 exec jekyll build'`, which is how I build some websites I have.

To me, that's not ok from an user experience point of view.

Exactly my point. You can already do it with direnv, have guix shell once you cd into dir and then just do `jekyll build`.

Does

  nix develop -c jekyll build

not do the job for you? (For a single development command—for deploy 'nix build' should be set up to do the right thing, including setting LC_ALL if necessary; and to enter a dev shell just 'nix develop' should work. Nixpkgs installs glibc with a full complement of locales by default, which has its downsides size-wise but should prevent any troubles when setting LC_ALL=fr_FR.)

Or, for an automatic setup,

  cat > .envrc
  use flake
  ^D

or, for an automatic setup with caching[1],

  cat > .envrc
  if ! has nix_direnv_version || ! nix_direnv_version 2.2.0; then
    source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/2.2.0/direnvrc" "sha256-5EwyKnkJNQeXrRkYbwwRBcXbibosCJqyIUuz9Xq+LRc="
  fi
  use flake
  ^D

(I don't have nix-direnv installed systemwide because it ignores the --no-write-lock-file flag I need to pass sometimes. If you put some of your config in default.nix or shell.nix or whatever, you’ll need to watch_file resp. nix_direnv_watch_file those.)

[1] https://github.com/nix-community/nix-direnv#direnv-source_ur...

Oh, in Nix, this works flawlessly, I was talking about Guix in the comment !

Use `setenv` inside the manifest.

    (setenv "MAMA" "MIA")
    (specifications->manifest (list "hello"))