$ stack --nix-help
Usage: stack [--[no-]nix] [--[no-]nix-pure] [--nix-packages NAMES] 
             [--nix-shell-file FILE] [--nix-shell-options OPTIONS] 
             [--nix-path PATH_OPTIONS] [--[no-]nix-add-gc-roots] OTHER ARGUMENTS

  Only showing --nix* options.

Available options:
  --[no-]nix               Enable/disable use of a Nix-shell. Implies
                           'system-ghc: true'.
  --[no-]nix-pure          Enable/disable use of a pure Nix-shell. Implies
                           '--nix' and 'system-ghc: true'.
  --nix-packages NAMES     List of packages that should be available in the
                           nix-shell (space separated).
  --nix-shell-file FILE    Nix file to be used to launch a nix-shell (for
                           regular Nix users).
  --nix-shell-options OPTIONS
                           Additional options passed to nix-shell.
  --nix-path PATH_OPTIONS  Additional options to override NIX_PATH parts
                           (notably 'nixpkgs').
  --[no-]nix-add-gc-roots  Enable/disable addition of packages to the nix GC
                           roots so nix-collect-garbage does not remove them.
                           (default: disabled)