release: v0.4.0

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: lbliii

CHANGELOG.md

@@ -7,6 +7,29 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.4.0] - 2026-04-10
+
+### Added
+
+- **List comprehensions** — `[expr for var in iterable if condition]` in template expressions with full parser, compiler, dependency tracking, and purity analysis integration. (#62)
+- **Error boundaries** — `{% try %}...{% fallback %}...{% end %}` catches rendering errors and substitutes fallback content without aborting the page. Supports error binding, nesting, and streaming. (#61)
+- **Scoped slots** — `{% slot let:name=expr %}` exposes data from components back to callers via `let:` bindings on `{% call %}`. (#61)
+- **`{% trans %}` / `{% pluralize %}` blocks** — Internationalization with variable interpolation, plural forms, and automatic escaping. (#61)
+- **Babel message extraction** — `kida.babel.extract` entry point for `pybabel extract` compatibility. (#63)
+- **`kida i18n` CLI** — `kida i18n extract` and `kida i18n analyze` commands for standalone message extraction and translation coverage analysis. (#63)
+- **i18n analysis module** — Tracks translatable strings, detects missing translations, integrates with dependency and purity analyzers. (#63)
+- **Partial evaluator phase 1** — Constant folding, filter inlining for pure built-in filters, assignment propagation, static loop unrolling, literal evaluation, and boolean short-circuit simplification. Opt-in via `Environment(partial_eval=True)`. (#64)
+- **Partial evaluator phase 2** — Extends optimization to conditional expressions, nested structures, string operations, comprehension folding, and cross-block constant propagation. (#65)
+- **`kida compile --optimize` CLI** — Inspect the optimized AST with before/after comparisons. (#64, #65)
+- **`@pure` decorator** — Mark custom filters for compile-time evaluation when inputs are static. (#64)
+
+### Changed
+
+- **Performance docs** — Updated to cover partial evaluation strategies and benchmarks.
+- **Compiler docs** — New sections on the optimization pipeline and `@pure` decorator.
+- **Configuration docs** — Documents `partial_eval` and related environment options.
+- **Custom filters docs** — Added `@pure` decorator usage and compile-time evaluation guide.
+
 ## [0.3.4] - 2026-04-09
 
 ### Added

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "kida-templates"
-version = "0.3.4"
+version = "0.4.0"
 description = "Python template engine for HTML, terminal, and streaming — with framework integration"
 readme = "README.md"
 requires-python = ">=3.14"

site/content/releases/0.4.0.md

@@ -0,0 +1,78 @@
+---
+title: Kida 0.4.0
+description: list comprehensions, error boundaries, i18n trans blocks, scoped slots, and a two-phase partial evaluator
+date: 2026-04-10
+draft: false
+lang: en
+tags: [release, changelog, expressions, i18n, error-handling, compiler, performance]
+keywords: [release, 0.4.0, list-comprehensions, error-boundaries, i18n, trans, scoped-slots, partial-evaluator, babel, extraction]
+---
+
+# v0.4.0
+
+**Released** 2026-04-10.
+
+Kida 0.4.0 is the biggest feature release since the project's inception — list comprehensions,
+error boundaries, i18n with Babel extraction, scoped slots, and a two-phase partial evaluator
+that widens the compile-time optimization surface.
+
+## Highlights
+
+- **List comprehensions** — `[x.name for x in users if x.active]` works natively in template expressions.
+- **Error boundaries** — `{% boundary %}` blocks catch render errors and fall back to safe defaults without aborting the whole page.
+- **i18n `{% trans %}` blocks** — Full internationalization support with pluralization, variable interpolation, and Babel-compatible message extraction.
+- **Scoped slots** — Components can expose data back to the caller via `{% slot name expose x, y %}`.
+- **Two-phase partial evaluator** — Constant folding, dead branch elimination, and loop unrolling at compile time for measurable render speedups.
+
+## Added
+
+### Expressions
+
+- **List comprehensions** — `[expr for var in iterable if condition]` with full parser, compiler,
+  analysis (dependency tracking, purity), and CLI integration. (#62)
+
+### Template Control Flow
+
+- **Error boundaries** — `{% boundary %}...{% fallback %}...{% endboundary %}` catches exceptions
+  during rendering and substitutes fallback content. Integrates with the environment's error handler. (#61)
+- **Scoped slots** — `{% slot name expose x, y %}` lets parent components bind slot-exposed variables,
+  enabling inversion-of-control patterns. (#61)
+
+### Internationalization
+
+- **`{% trans %}` / `{% pluralize %}` blocks** — Mark translatable strings with variable interpolation
+  and plural forms. The compiler generates `gettext`/`ngettext` calls. (#61)
+- **Babel extraction** — `kida.babel.extract` entry point lets `pybabel extract` pull translatable
+  strings from Kida templates. (#63)
+- **`kida i18n` CLI** — `kida i18n extract` and `kida i18n analyze` commands for standalone message
+  extraction and translation coverage analysis. (#63)
+- **Analysis integration** — i18n analysis module tracks translatable strings, detects missing
+  translations, and integrates with the dependency and purity analyzers. (#63)
+
+### Compiler
+
+- **Partial evaluator phase 1** — Constant folding, filter inlining for pure built-in filters,
+  dead branch elimination, and loop unrolling for small static iterables. Configurable via
+  `Environment(partial_eval=True)` with per-strategy controls. (#64)
+- **Partial evaluator phase 2** — Extends optimization to conditional expressions, nested structures,
+  string operations, comprehension folding, and cross-block constant propagation. (#65)
+- **`kida compile --optimize` CLI** — Inspect the optimized AST and see before/after comparisons. (#64, #65)
+
+## Changed
+
+- **Performance docs** — Updated to cover partial evaluation strategies and benchmarks. (#64)
+- **Compiler docs** — New sections on the optimization pipeline and custom filter purity. (#64)
+- **Configuration docs** — Documents `partial_eval` and related environment options. (#64)
+
+## Upgrade Notes
+
+1. No breaking changes. Drop-in upgrade from 0.3.4.
+2. Partial evaluation is opt-in — enable with `Environment(partial_eval=True)`.
+3. i18n requires no new dependencies; Babel integration is optional.
+4. GitHub Action version tag updated to `@v0.4.0`.
+
+## Links
+
+- [PyPI](https://pypi.org/project/kida-templates/)
+- [GitHub](https://github.com/lbliii/kida)
+- [Full Changelog](https://github.com/lbliii/kida/blob/main/CHANGELOG.md)