Module system's merging algorithm and differences between `lib.mkMerge`, `lib.mkIf` & `lib.attrsets.mergeAttrsList`, `lib.optionals`.

ryan4yin / nixos-and-flakes-book

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Module system's merging algorithm and differences between `lib.mkMerge`, `lib.mkIf` & `lib.attrsets.mergeAttrsList`, `lib.optionals`. #106

Open ryan4yin opened 4 months ago

ryan4yin commented 4 months ago

Related to:

https://discourse.nixos.org/t/best-resources-for-learning-about-the-nixos-module-system/1177/4
https://nixos-and-flakes.thiscute.world/other-usage-of-flakes/module-system
lib.mkMerge & lib.mkIf is used by module system for lazy evaluation & mergeing, while lib.attrsets.mergeAttrsList & lib.optionals is only little nix functions. It's recommend to use lib.mkMerge & lib.mkIf only inside imports = [ ... ] and config = { ... }.

piyoki commented 4 months ago

References:

https://noogle.dev/f/lib/mergeAttrsList - for lib.attrsets.mergeAttrsList