cue-lang/cue v0.15.0-alpha.1

on GitHub

This release removes the old evalv2 evaluator, adds the explicitopen language experiment, and introduces an initial version of cue lsp.

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

Evaluator

⚠️ Removing evalv2

The old evalv2 evaluator, which previously could be re-enabled via CUE_EXPERIMENT=evalv3=0, is now deleted. The new evalv3 evaluator has been on by default since v0.13.0, and at this point our entire test suite including Unity is working.

Removing the old evaluator reduces significant load on development, as we were able to clear out four thousand lines of code and simplify the internal types and code structure. This is a necessary step to unblock upcoming feature work in the evaluator.

As a bonus, because the old and new evaluators shared many core evaluator types, removing the fields only used by the old evaluator yields modest memory usage improvements around 4-6%.

explicitopen experiment for #A...

The explicitopen experiment enables the posfix ... operator to explicitly open closed structs, allowing additional fields to be added. This is a breaking change to the language which we are starting to transition towards; many users found the existing embed semantics to be confusing.

Furthermore, the existing semantics greatly complicated the evaluator and prevented significant performance optimizations. The new semantics also resolve a number of limitations, such as not being able to enforce a schema at the package level without opening up the schema due to the necessary embedding.

Once a module's language.version targets v0.15.0, this can be enabled via the file attribute @experiment(explicitopen). To automatically convert files or packages to the new semantics, use cue fix --exp=explicitopen. Once the proposal is accepted, we intend to provide a command to safely upgrade a module to use the new semantics, without affecting its dependencies nor dependents.

For more information, see the proposal on GitHub and the spec change patch.

Other changes

A number of panics and error regressions in the evaluator which were reported in the last month have been fixed; thank you to all who reported these.

Dependency analysis now avoids computing references more than once, which resolves an expontential performance issue for some configurations using chains of CUE references.

Evaluating concrete CUE values no longer involves dependency analysis; this should result in modest speed improvements for users of standard library APIs such as yaml.Marshal.

Some error positions which were lost in the transition from evalv2 to evalv3 have been reintroduced by a few fixes.

File embedding via the @embed attribute has gained an allowEmptyGlob option, to allow glob patterns to match zero files without causing an error.

cmd/cue

The cue fix --exp flag is introduced to rewrite files or packages to use new and experimental semantics with @experiment attributes.

cue get go now stops if loading the given Go packages resulted in any errors. We would previously try to continue in the presence of some syntax or type-checking errors, but this could easily lead to subtle bugs such as panics or generated CUE which was incomplete or incorrect.

LSP

This alpha release includes the initial version of cue lsp - with support for "go to definition", code completion, hover documentation, and code formatting.

See our Getting Started wiki page for instructions on how to set it up with your editor.

Please report any bugs or missing features you encounter via the Issue tracker or via the #lsp channels on either Discord or Slack.

Encodings

The Protobuf decoder has been tweaked to not require files such as google/protobuf/timestamp.proto to exist on disk, given that they are mapped to CUE standard library APIs directly.

The Protobuf decoder has also been tweaked to support fully qualified references such as my.pkg.name.MessageName.

A bug is fixed in the TOML decoder where subtable keys could incorrectly lead to duplicate key errors.

Standard library

The net package has gained new AddIP and AddIPCIDR functions to add numerical offsets to IP addresses or CIDR networks.

The Atoi, ParseInt, and ParseUint functions in the strconv package now work on integers with unlimited precision, like the rest of the CUE evaluator, rather than just a maximum of 64 bits.

Go API

encoding/json gains JSON Pointer APIs, which are already useful in packages like encoding/jsonschema.

cue/ast introduces PostfixExpr to support upcoming additions to the language syntax.

tools/fix has gained new APIs to fix configs to use an active experiment, as well as fixing configs to a newer language version.

cue introduces a Path.Append convenience method.

cue/token is adjusted so that node positions within a file never result in an offset which is outside the bounds of the file. This could easily lead to subtle bugs or panics when using node position offsets.

cue/errors is adjusted so that Positions only collects printable positions, to prevent printing empty positions in the CLI.

cue/ast deprecates the File.Imports field in favor of the File.ImportSpecs iterator method. The iterator method File.ImportDecls is also introduced for completeness.

⚠️ The long-deprecated cue.ResolveReferences option API is now removed.

cue/parser.DeprecationError.Version is deprecated, as tracking CUE language versions via integers has not been used since v0.4.3, and the mechanism was never properly documented.