Lyric

A statically typed application language with a bytecode VM — standalone, and embeddable in a host with a capability-based sandbox.

What changed in v4.4.1 — 2026-09-04

Round 1 of the sweep after M36. Two findings, both older than the feature that surfaced them.

A pattern may no longer bind the same name twice (LYR-SEM0097). P { n, n }, P { n = x, m = x } and E.B(x, x) each name one binding twice, and the second was dropped in silence: P { n = 7, m = 9 } matched against P { n = x, m = x } answered 7. The mirror image had always been refused — LYR-SEM0070 for a duplicate field in an initializer — so one brace list answered the same question two ways depending on whether you were constructing or destructuring.

Shadowing a name from an enclosing scope is untouched, and so is an or-pattern, whose alternatives are required to repeat the same names.
An or-pattern that binds is refused by name. E.A(x) | E.B(x) never lowered: each alternative is a branch of its own and would have to bind on its own path, while the binding step runs once for the whole pattern. It said nothing about that, so the first use of a bound name failed as reference to 'x' — a message about a name that only looks undeclared. An or-pattern that binds nothing, which is what the form is usually for, is unaffected.