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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/manual/rl-next/repl-overlays.md | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/doc/manual/rl-next/repl-overlays.md b/doc/manual/rl-next/repl-overlays.md new file mode 100644 index 000000000..9f48cf381 --- /dev/null +++ b/doc/manual/rl-next/repl-overlays.md @@ -0,0 +1,36 @@ +--- +synopsis: Add `repl-overlays` option +prs: 10203 +cls: 504 +--- + +A `repl-overlays` option has been added, which specifies files that can overlay +and modify the top-level bindings in `nix repl`. For example, with the +following contents in `~/.config/nix/repl.nix`: + +```nix +info: final: prev: let + optionalAttrs = predicate: attrs: + if predicate + then attrs + else {}; +in + optionalAttrs (prev ? legacyPackages && prev.legacyPackages ? ${info.currentSystem}) + { + pkgs = prev.legacyPackages.${info.currentSystem}; + } +``` + +We can run `nix repl` and use `pkgs` to refer to `legacyPackages.${currentSystem}`: + +```ShellSession +$ nix repl --repl-overlays ~/.config/nix/repl.nix nixpkgs +Lix 2.90.0 +Type :? for help. +Loading installable 'flake:nixpkgs#'... +Added 5 variables. +Loading 'repl-overlays'... +Added 6 variables. +nix-repl> pkgs.bash +«derivation /nix/store/g08b5vkwwh0j8ic9rkmd8mpj878rk62z-bash-5.2p26.drv» +``` |