Ordered maps
The Linux x86-64 direct lowerer implements Map<K,V> for the language's four key types: i32, u8, bool, and string. Values may use the other supported recursive aggregate types, including nested maps. Target availability depends on the selected installation and release.
map_new, map_len, map_get, map_set and map_remove, structural equality and snapshot iteration preserve the existing Core schema and language semantics. Integer keys sort numerically without overflow-prone subtraction. Boolean keys sort false before true; strings compare unsigned UTF-8 bytes, preserving NULs and normalization differences. Equal-content strings replace the existing entry. Iteration supports the same irrefutable patterns as arrays, including a single tuple binding or a destructured (key,value) pattern.
Private layout and ownership
Object metadata records mapLayout: kelft-native-maps/1. A map is an owned-pointer array of key/value tuple objects in sorted order. Each tuple uses the existing 40-byte heap header, two eight-byte field slots and a mixed-ownership bitmap. The map array owns its entries; each entry owns its aggregate key/value fields. Empty maps are allocated owned arrays. There is no public pointer or map layout.
Trusted Kelft builders in selfhost/direct/map-runtime.kelft emit k_map_compare, k_map_lower_bound and k_map_splice. They use the existing four-pointer runtime ABI. Comparison and search borrow a raw key cell and never allocate, retain, release or modify inputs. Scalar key cells contain i32 (u8 keys are widened before marshalling); string key cells contain a borrowed pointer. Comparison/search return i32 and write exactly four result bytes. The scalar comparator returns -1/0/1, and the string comparator returns a signed ordering value.
Splice borrows the map and optional entry and returns an owned array. Its index is in [0,length]; removal count is zero or one and cannot exceed the remaining entries. A null entry means deletion, otherwise it inserts one retained entry. The existing allocation checks reject excessive output length before multiplying by eight. These helpers are private trusted mechanisms, not general FFI.
Source lowering evaluates each location and argument once, left to right. Set and remove resolve the evaluated location against its current root after argument evaluation. Set builds a new entry and array, then makes enclosing owners unique before replacing their map cell. Missing remove returns false without allocating or cloning enclosing owners. Get returns an owned Option and retains an aggregate value; replacing/removing its source does not invalidate it. Updates preserve aliases, retained iteration snapshots and owned loop bindings. Frame cleanup and the entry wrapper's zero-live-charge assertion also cover maps.
Binary search takes logarithmically many key comparisons; string comparisons may scan their bytes. Successful updates copy array entries linearly. This conservative representation establishes semantics; it does not claim efficient compiler bootstrap or native performance. The graph runtime adds recursive layouts and iterative equality.
Verification requirements
Map checks must cover every key type, signed boundaries, Unicode/NUL ordering, replacement and removal, structural equality, nested ownership, evaluated locations, retained get results, snapshots, and heap exhaustion. ABI checks must verify sorted entries, borrowed inputs, allocation-free search, owned outputs, four-byte result writes, exact key-cell reads, reclamation, and rejection of invalid input or growth before unsafe copying. Invalid signatures, key layouts, and iteration patterns must fail before object emission.
Source: public Kelft compiler, commit f567c21684362db37e0aa0a68e71e7614502c45a. Compiler 0.1.0-alpha.2; Core 0.1; Intent 0.2.