39 lines
854 B
Markdown
39 lines
854 B
Markdown
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# Formatter and Checks
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This note covers `16-formatter-and-checks/`, which exposes `formatter.<system>` and a small `checks.<system>.*` derivation that uses the same formatter.
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---
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## 1. Why These Outputs Matter
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Two flake outputs are especially practical in day-to-day use:
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- `formatter.<system>`, which powers `nix fmt`, and
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- `checks.<system>.*`, which powers `nix flake check`.
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This example keeps both outputs small so the wiring is obvious.
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---
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## 2. The Important Connection
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The flake points `formatter.<system>` at `pkgs.nixfmt`, then reuses that same formatter in a check:
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```nix
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formatter.${system} = pkgs.nixfmt;
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```
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That shows the main idea: a formatter output is just another derivation, so checks can use it too.
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---
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## 3. Commands to Try
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```bash
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cd 16-formatter-and-checks
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nix fmt sample.nix
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nix flake show
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nix flake check
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```
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