feat: execute readonly type-valued compile-time slices

README.md

@@ -130,6 +130,8 @@ ordinary procedures also accept `undefined` as the initializer of a mutable loca
 
 procedures returning fixed arrays or records/tuples containing `type`, such as `types proc() [2]type { return [i16, bool] }` or `config proc() struct { child type, count usize } { return { child = i16, count = 2 } }`, execute entirely at compile time. every argument is explicitly supplied, constant, cached and erased; nested/aliased results, empty shapes and dependent `$N` lengths retain exact shape and mutability. compile-time producers accept ordinary type-array/type-record inputs, and runtime generic procedures accept erased `$` parameters with these shapes. direct projections generate signatures, constructors, storage and defaults; explicit `$()` calls inside producers retain owned values. cache identity uses canonical type leaves without merging distinct nominal types, and copies cannot mutate cached inputs/results. imported diagnostics, shared type-control execution limits and repeatable compilation work through interpreter/native execution. ordinary parameters remain excluded from dependent signatures; use `$N` for lengths. runtime type-array/type-record storage and reflection remain open.
 
+readonly type-valued slices (`[]type` and slices of metadata records/arrays) also cross compile-time procedure boundaries as owned snapshots. contextual array literals, including `[]`, construct them; explicit views of immutable readonly arrays and existing metadata slices support checked `usize` bounds, empty end views, indexing and `.len`. nested slices, ordinary/inline by-value iteration, erased `$` inputs and optional/fallible channels retain exact nominal leaves and content-based specialization identity. snapshots generate runtime types/defaults, but metadata itself has no runtime storage. mutable slice types, sentinels and views of mutable array places remain rejected rather than silently losing borrowing semantics; copy an array into an immutable binding before taking an owned view. construction shares the type-control step bound, and uninitialized leaves cannot cross procedure boundaries.
+
 optional `if`/`while` captures also execute in type-producing bodies: `if count |length| { return [length]i16 }` generates storage from an optional `usize`. ordinary checked IR validates each executed guard; present payloads become immutable owned constants with exact scalar/aggregate types and strings, and absent optionals skip the body. while guards observe updated locals on each iteration; captures stay body-local across break/continue and early return. generated lengths/defaults, imported producers, cache identity and repeated compilation preserve these values. null data/function pointers materialize as null; callbacks retain source declaration identity, while nonnull data pointers and unsupported slice types retain the constant-materialization escape boundary.
 
 type-producing bodies also execute scalar/enum `match` statements and type-valued match expressions in initializers, assignments and returns, such as `return match wide { true: i16, false: i8 }`. selected expression arms may themselves be matches. an ordinary checked IR match returns the selected arm index, preserving subject/pattern typing, range boundaries, overlap, unreachable-arm and exhaustiveness diagnostics without checking unexecuted bodies. statement arms retain scoped locals, assignments, early returns and enclosing-loop break/continue; expression selection shares the type-control step bound.