60b7121d2c
We want to be able to write down `foo.drv^bar.drv^baz`:
`foo.drv^bar.drv` is the dynamic derivation (since it is itself a
derivation output, `bar.drv` from `foo.drv`).
To that end, we create `Single{Derivation,BuiltPath}` types, that are
very similar except instead of having multiple outputs (in a set or
map), they have a single one. This is for everything to the left of the
rightmost `^`.
`NixStringContextElem` has an analogous change, and now can reuse
`SingleDerivedPath` at the top level. In fact, if we ever get rid of
`DrvDeep`, `NixStringContextElem` could be replaced with
`SingleDerivedPath` entirely!
Important note: some JSON formats have changed.
We already can *produce* dynamic derivations, but we can't refer to them
directly. Today, we can merely express building or example at the top
imperatively over time by building `foo.drv^bar.drv`, and then with a
second nix invocation doing `<result-from-first>^baz`, but this is not
declarative. The ethos of Nix of being able to write down the full plan
everything you want to do, and then execute than plan with a single
command, and for that we need the new inductive form of these types.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
22 lines
1.2 KiB
Markdown
22 lines
1.2 KiB
Markdown
# Release X.Y (202?-??-??)
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- Two new builtin functions,
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[`builtins.parseFlakeRef`](@docroot@/language/builtins.md#builtins-parseFlakeRef)
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and
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[`builtins.flakeRefToString`](@docroot@/language/builtins.md#builtins-flakeRefToString),
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have been added.
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These functions are useful for converting between flake references encoded as attribute sets and URLs.
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- [`builtins.toJSON`](@docroot@/language/builtins.md#builtins-parseFlakeRef) now prints [--show-trace](@docroot@/command-ref/conf-file.html#conf-show-trace) items for the path in which it finds an evaluation error.
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- Error messages regarding malformed input to [`derivation add`](@docroot@/command-ref/new-cli/nix3-derivation-add.md) are now clearer and more detailed.
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- The `discard-references` feature has been stabilized.
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This means that the
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[unsafeDiscardReferences](@docroot@/contributing/experimental-features.md#xp-feature-discard-references)
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attribute is no longer guarded by an experimental flag and can be used
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freely.
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- The JSON output for derived paths with are store paths is now a string, not an object with a single `path` field.
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This only affects `nix-build --json` when "building" non-derivation things like fetched sources, which is a no-op.
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