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cefd0302b5
desugaring inherit-from to syntactic duplication of the source expr also duplicates side effects of the source expr (such as trace calls) and expensive computations (such as derivationStrict).
8 lines
409 B
Markdown
8 lines
409 B
Markdown
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synopsis: "`inherit (x) ...` evaluates `x` only once"
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prs: 9847
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`inherit (x) a b ...` now evaluates the expression `x` only once for all inherited attributes rather than once for each inherited attribute.
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This does not usually have a measurable impact, but side-effects (such as `builtins.trace`) would be duplicated and expensive expressions (such as derivations) could cause a measurable slowdown.
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