37 lines
926 B
Markdown
37 lines
926 B
Markdown
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---
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synopsis: Add `repl-overlays` option
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prs: 10203
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cls: 504
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---
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A `repl-overlays` option has been added, which specifies files that can overlay
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and modify the top-level bindings in `nix repl`. For example, with the
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following contents in `~/.config/nix/repl.nix`:
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```nix
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info: final: prev: let
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optionalAttrs = predicate: attrs:
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if predicate
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then attrs
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else {};
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in
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optionalAttrs (prev ? legacyPackages && prev.legacyPackages ? ${info.currentSystem})
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{
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pkgs = prev.legacyPackages.${info.currentSystem};
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}
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```
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We can run `nix repl` and use `pkgs` to refer to `legacyPackages.${currentSystem}`:
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```ShellSession
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$ nix repl --repl-overlays ~/.config/nix/repl.nix nixpkgs
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Lix 2.90.0
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Type :? for help.
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Loading installable 'flake:nixpkgs#'...
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Added 5 variables.
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Loading 'repl-overlays'...
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Added 6 variables.
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nix-repl> pkgs.bash
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«derivation /nix/store/g08b5vkwwh0j8ic9rkmd8mpj878rk62z-bash-5.2p26.drv»
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```
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