struct type construction

LANGUAGE.md

@@ -177,20 +177,24 @@ exactness follows floating-point equality. Other float NaN and infinity behavior
 underlying IEEE operations. Ordinary float `/` remains unchecked and therefore preserves IEEE
 infinity/NaN behavior.
 
-Only the six bang calls are intrinsic. Bare calls such as `divfloor(a, b)` and qualified calls such
-as `math.divfloor(a, b)` resolve to ordinary functions.
+Only these six division bang calls select integer-division behavior. Bare calls such as
+`divfloor(a, b)` and qualified calls such as `math.divfloor(a, b)` resolve to ordinary functions.
 
 ### functions, C interop, and linking
 
 - demand-monomorphized Brolang and C-ABI functions
 - integer comptime value parameters such as `make_array func($N usize) [N]u8`, specialized by value and omitted from the runtime ABI
 - explicit comptime type parameters such as `max func($T type, a, b T) T`, specialized by type and omitted from the runtime ABI
+- later comptime value parameters may depend on earlier type parameters, as in `factory func($T type, $default T) type`
 - comptime parameters may appear anywhere, are erased from the runtime ABI, and accept recursively stable booleans, integers, floats, types, immutable bytes, enums, fixed arrays, records/tuples, optionals, tagged unions, and bare function identities; equal structural values and aliases of one function declaration share specializations, while distinct declarations remain distinct and pointers, general slices, fallibles, ranges, untagged unions, and undefined values have no stable comptime identity
 - comptime parameters may be omitted when uniquely recoverable from runtime arguments, the immediate expected result, or exact type-factory provenance; `_` is an explicit inference hole
 - forced typed comptime expressions such as `$sum(1, 2)`, `$Point { x = 1, y = 2 }`, and comptime value blocks such as `${ yield 4 }`
 - comptime execution for bodyful Brolang functions with mutable locals, loops, `defer`, `match`, `try`/`catch`, exact type `==`/`!=`, pointer/slice storage mutation, pointer captures, and calls through comptime-known function values; `undefined` storage may be initialized at comptime, but remaining poison cannot be observed
 - comptime type factories such as `Box func($T type) type { return struct { value T } }`; calls like `Box(i32)` are concrete nominal types and may appear anywhere a type is expected
+- `struct_type!(layout, names, types, defaults)` constructs a nominal record type from comptime fixed arrays or tuples and is valid in every type position; layout is `.auto` or `.c`, bare `none` means a required field, and `some!(none)` installs an optional `none` default
+- `some!(value)` explicitly constructs the present branch of an expected optional, including nested optionals where `some!(none)` differs from outer `none`
 - tuple types are unnamed-field structs (`struct { i32, []u8 }`), tuple values use `{1, "bro"}` / `{1,}` / `{}`, and fields use canonical numeric names such as `.0`
+- anonymous keyed records use `{x = 1, name = "bro"}`; without context their declaration-ordered names and inferred value types form a structurally interned record type, while a record context applies that type's coercions and field defaults; `{}` remains an empty tuple without context and constructs an empty contextual record when a record is expected
 - `typeinfo!`, `field!`, `compile_error!`, and semantic `expand for` provide compile-time record and enum reflection and heterogeneous static expansion without runtime metadata; enum reflection exposes declaration-ordered fields, reflected aggregates remain persistent compile-time values, and expand-loop `break` / `continue` must be selected entirely at comptime
 - `tag!(value)` reads a tagged union's active discriminant and folds when the value is comptime-known; `tagname!(enum_value)` requires a comptime-known enum value and returns its immutable declaration name
 - bodyful `c_func` definitions and bodyless `c_func` declarations with exact external symbol names
@@ -213,6 +217,7 @@ as `math.divfloor(a, b)` resolve to ordinary functions.
 - root `std` re-exports `ArrayList(T)` while its operations remain in `std/arraylist`
 - `std/mem` generic slice equality, allocator contract with raw byte operations, typed `empty` / `alloc` / `realloc` / `free`, overflow checks, zero-sized-type support, and failure-preserving reallocation
 - `std/arraylist` generic `ArrayList(T)` with direct `items` slice access, explicit capacity, allocator ownership, fallible reserve/append, clear, and deinit
+- `std/meta` reflection records plus `EnumFieldStruct(E, Field, default ?Field)`, implemented with `struct_type!`; it produces a record with one field per native enum member in declaration order, where outer `none` means no field default
 - `std/io` explicit `Io` capabilities, provider-bound `Reader`/`Writer` handles, existing-file open/close operations, allocation-free `write_all`, and comptime-expanded writer-first `print`; formatting supports natural `{}`, byte `{s}`, decimal `{d}`, integer `{b}` / `{o}` / `{x}` / `{X}`, byte-character `{c}`, scientific float `{e}`, and `{{` / `}}`, with malformed formats and incompatible tuple fields rejected at comptime
 - entry points are either `main func() ...` or `main func(init process.Init) ...`; `std/process.Init` carries startup capabilities, currently only `io`, while the system provider remains hidden inside `std/io`
 - `std/debug.print` is an allocation-free, failure-ignoring stderr escape hatch independent of `process.Init`