cue-lang/cue v0.15.0-alpha.3

on GitHub

Changes which may break some users are marked below with: ⚠️

Evaluator

aliasv2 experiment

⚠️ The self experiment introduced in v0.15.0-alpha.2 has been renamed to aliasv2, to fully implement the Postfix Aliases proposal on GitHub.

Adding a new experiment like @experiment(postfixalias) alongside @experiment(self) was not a good option given that cue fix can only adjust existing code correctly when both experiments are enabled. Allowing the use of just one half of the experiment would add too many tricky edge cases.

Once a module's language.version targets v0.15.0, this can be enabled via the file attribute @experiment(aliasv2). You can use cue fix --exp=aliasv2 to transition existing CUE code in a module to the new alias syntax and semantics.

Other changes

Fix a bug where required fields in a definition might not be enforced when unifying with an inline struct in an expression, such as (#RequiresFoo & {bar: "baz"}).bar.

Fix a bug where a value's reference to self through a let declaration would hang the evaluator.

Add caching to a part of the typochecker algorithm; this has been measured to provide speed-ups of up to 30% on a few large projects.

cmd/cue

cue mod mirror now copies OCI referrers between registries, which ensures that artifacts like signatures and attestations which reference modules being mirrored are copied as well.

cue get go gains an --outfile flag to generate exactly one CUE file for a single Go package, which can be useful when integrating cue get go into build systems like Bazel.

Encodings

Initial support for encoding CUE schemas as JSON Schema is added. This includes a new encoding/jsonschema.Generate Go API, as well as CLI support via cue def --out jsonschema. This is very experimental as yet, and many features are missing. For now, it can only generate a single version of JSON Schema (draft/2020-12).

The YAML encoder no longer uses CUE's dependency analysis algorithm. This helps prevent panics that some users had run into with cue export -e expr --out yaml.

Go API

The new cue.Value.IsClosed and cue.Value.IsClosedRecursively methods report whether a value has been closed at the top level or recursively, which is useful information when writing schema encodings.

The new cue.Patterns and cue.Selector.Pattern APIs allow introspecting pattern constraints in CUE struct values.