Changelog

This file tracks user-visible Lyng language/runtime/tooling changes.

History note:

The project had periods where changelog maintenance lagged behind commits.
Entries below are synchronized and curated for 1.5.x.
Earlier history may be incomplete and should be cross-checked with git tags/commits when needed.

1.5.1 (2026-03-25)

Added string interpolation:
- "$name" identifier interpolation.
- "${expr}" expression interpolation.
Added literal-dollar forms in strings:
- "\$" -> $
- "$$" -> $
- \\$x is parsed as backslash + interpolation of x.
Added per-file interpolation opt-out via leading directive comment:
- // feature: interpolation: off

Updated compiler-accurate AI language docs:
- interpolation syntax and escaping
- per-file feature switch behavior
Refreshed tutorial examples and doctests to reflect new interpolation semantics.
Added/reworked current proposal/reference materials for Lyng common-platform guidance.

Interpolation is enabled by default for normal string literals.
Existing code that intentionally used $name as literal text should use \$name, $$name, or the file directive // feature: interpolation: off.

Completed migration to bytecode-first/bytecode-only execution paths.
Removed interpreter fallback behavior in core execution hot paths.
Continued frame-slot-first local/capture model improvements and related diagnostics.

Added/finished return semantics including labeled non-local forms (return@label).
Added abstract classes/members and interface support (as abstract-class-style construct).
Completed and enabled multiple inheritance with C3 MRO by default.
Added class properties with accessors (get/set) and restricted setter visibility (private set, protected set).
Added late-initialized class val support with Unset protection rules.
Added named arguments (name: value) and named splats (...map) with stricter validation.
Added assign-if-null operator ?=.
Improved nullable/type-checking behavior (including T is nullable and related type checks).
Added variadic function types (... in function type declarations) and tighter lambda type checks.

Added immutable collections hierarchy (ImmutableList, ImmutableSet, ImmutableMap).
Improved generic runtime binding/checking for explicit type arguments and bounds.
Added smarter type-aware collection ops (+=, -=) and stronger declared-member type checks.

Tightened extern declaration rules:
- explicit extern members are required for extern class/object declarations.
Improved extern generic class behavior and diagnostics.
Extended bridge APIs for binding global functions/variables and object/member interop scenarios.

Added lyng.observable improvements (ObservableList hooks/events).
Added Random stdlib API used by updated samples.
Added/extended lyngio.console support and CLI integration for console interaction.
Migrated time APIs to kotlin.time (Instant migration and related docs/tests).

CLI:
- added first-class fmt command
- preserved direct script fast-path invocation
- improved command help/dispatch behavior
IntelliJ plugin:
- improved lightweight completion and documentation/inspection behavior
- continued highlighter and Grazie/spellchecking integration work
Docs:
- substantial updates across tutorial/OOP/type/runtime references
- expanded bytecode and advanced topics coverage

If you rely on literal $... strings:
- replace with \$... or $$..., or
- add // feature: interpolation: off at file top.
Review any code relying on interpreter-era fallback behavior; 1.5.x assumes bytecode-first execution.
For extern declarations, ensure members are explicitly declared where required.
For named arguments/splats, verify call sites follow stricter ordering/duplication rules.