Qyriad
b3e24cb3e5
Co-authored-by: Emilia Bopp <contact@ebopp.de> Change-Id: I3c3347e51d8543fbeb2b4e6ed12b0f556a6a6964
16 lines
901 B
Markdown
16 lines
901 B
Markdown
---
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synopsis: "Add `builtins.warn` for emitting warnings from Nix code"
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cls: [2248]
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category: "Features"
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credits: [milibopp, Qyriad]
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---
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Lix now has a builtin function for emitting warnings.
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Like `builtins.trace`, it takes two arguments: the message to emit, and the expression to return.
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_Unlike_ `builtins.trace`, `builtins.warn` requires the first argument — the message — to be a string.
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In the future we may extend `builtins.warn` to accept a more structured API.
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To go along with this, we also have two new config settings:
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- [`debugger-on-warn`](@docroot@/command-ref/conf-file.md#conf-debugger-on-warn), which, when used with `--debugger`, makes `builtins.warn` also function like [`builtins.break`](@docroot@/language/builtins.md#builtins-break).
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- [`abort-on-warn`](@docroot@/command-ref/conf-file.md#conf-abort-on-warn), which aborts evaluation entirely after the warning is emitted.
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