cue-lang/cue v0.17.0-alpha.2

on GitHub

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

Language

The parser now allows a newline or a comma before the closing bracket of an index expression, matching how lists and func arguments allow omitting trailing commas:

foo[
    "bar"
]

Evaluator

The comprehension algorithm now waits to run a comprehension's body until the fields it reads have a concrete value, rather than trying to produce its fields up front. This resolves a number of long-standing bugs, most notably the last known regressions from evalv2, where a comprehension that should have resolved instead failed as an incomplete value or a cycle.

This design also greatly simplifies upcoming evaluator work, such as introducing new builtins to replace comparing values to bottom, as well as the design of evalv4.

The evaluator no longer deduplicates errors just by position, which was causing some useful errors from disjunctions or standard library calls to be dropped incorrectly.

A number of bugs, panics, and hangs have been resolved as well.

cmd/cue

cue vet -d/--schema now supports hidden fields, and correctly reports an error when the command inputs are CUE only.

cue fix and cue trim no longer change file modification times when no changes are necessary.

Encodings

⚠️ The experimental JSON Schema encoder now emits most definitions without the leading # character, shortening names and ensuring compatibility with the wider JSON Schema ecosystem. This required deprecating encoding/jsonschema.GenerateConfig.NameFunc in favor of NamesFunc.

Several closedness bugs in the JSON Schema encoder have been fixed, ensuring that the generated JSON Schema behaves the same way as the original CUE definition.

The ProtoBuf decoder now resolves relative references following the usual scoping rules, instead of always resolving them against the top-level scope.

Go API

Add Path.Compare and Selector.Compare, providing allocation-free total ordering suitable for slices.SortFunc.