Standard Library Support

Type Registry

All 586 stdlib type entries are registered with the semantic analyser so name resolution + protocol conformance checks work. The list below highlights notable types per kind. Full table: modules/stdlib/type_decls/module_stubs.c.

By kind (totals)586 entries

struct

240 entries — value types (Int family, Float family, Bool, String, Array, Dictionary, Set, Range…).

protocol

111 entries — Sequence, Collection, Equatable, Hashable, Comparable, BinaryInteger, BinaryFloatingPoint, etc.

enum

33 entries — Optional, Result, Unicode, FloatingPointRoundingRule, etc.

class

11 entries — KeyPath family, NSObject, JSONEncoder/Decoder, DateFormatter, UserDefaults.

typealias

186 entries — C interop aliases (CChar, CInt, CDouble…), legacy literal-protocol aliases.

Numeric types18 structs

Int / UInt

Default platform-width signed/unsigned integer (64-bit on WASM).

Int8 / UInt8

Fixed-width 8-bit integers.

Int16 / UInt16

Fixed-width 16-bit integers.

Int32 / UInt32

Fixed-width 32-bit integers.

Int64 / UInt64

Fixed-width 64-bit integers — native WASM size.

Int128 / UInt128

Declared in registry; runtime ops fall back to 64-bit.

Float / Double

IEEE 754 single + double precision; full math runtime.

Float16 / Float80

Registered; arithmetic widens to Double internally.

Bool

Native i32; standard logical / comparison ops.

Decimal

Type registered; high-precision arithmetic limited.

Collections13 structs + 2 enums

Array

Random-access; 39 runtime ops (append, sort, filter, map, slice, contains…).

ArraySlice

View into Array — shares underlying storage.

ContiguousArray

Same impl as Array on WASM.

Dictionary

Hash-keyed; 30 runtime ops (get, set, remove, merge, keys, values, iter…).

Set

Unordered unique elements; 33 ops including union, intersection, subset, symmetric_difference.

Range / ClosedRange

Half-open + closed bounds; iterable, contains.

RangeSet

Type registered; collection-of-ranges ops not yet wired.

Slice

Generic collection slice.

Optional

enum — `.some(T)` / `.none`; pattern matching, optional chaining, ??.

Result

enum — `.success(T)` / `.failure(E)` with throw/get bridge.

String & Character8 entries

String

Unicode 17.0 grapheme-cluster aware; 56 runtime ops (concat, split, contains, prefix/suffix, case, replace, slice, interp).

Substring

String view; shares storage, converts back via `String(_:)`.

Character

Single extended grapheme cluster.

Unicode.Scalar

21-bit code point; UTF8/16/32 view enums registered.

UTF8Span

Span-based UTF8 view (Swift 6); registered, ops basic.

StaticString

Compile-time string literal.

Notable protocols15 of 111

Equatable

== / !=. Auto-synthesised for structs/enums where eligible.

Hashable

hash(into:) for Set / Dictionary key use.

Comparable

< / > / sort.

Sequence

makeIterator + for-in.

Collection

Indexed access + count.

BinaryInteger

Integer protocol hierarchy.

BinaryFloatingPoint

Float / Double surface protocol.

Numeric / AdditiveArithmetic

+ - * / generic constraints.

Codable / Encodable / Decodable

Protocols registered; encoder/decoder runtime via Foundation bridge.

Error

throws / try / catch wired through async runtime.

CaseIterable

enum allCases auto-synthesis.

CustomStringConvertible

.description for print + interpolation.

ExpressibleBy*Literal

Full literal-protocol family for type-driven literals.

Sendable

Concurrency marker; isolation enforcement basic.

Copyable / Escapable

Swift 6 ownership protocols recognised.

Runtime Functions

Functions linked into stdlib.wasm and called from compiled user code. Names follow the __<module>_<op> convention.

String — string_rt.c56 functions

__str_concat / __str_eq / __str_neq / __str_lex_precedes

Concatenation, equality, lex comparison.

__str_len / __str_grapheme_len / __str_codepoint_count

UTF-8 byte length, grapheme cluster count, scalar count.

__str_substr / __str_prefix / __str_suffix / __str_grapheme_slice

Slicing — byte-, grapheme-, and prefix/suffix-aware.

__str_split / __str_split_ex / __str_join_array

Split by separator (basic + extended) and join.

__str_contains / __str_has_prefix / __str_has_suffix

Predicate searches.

__str_lowercased / __str_uppercased / __str_unicode_lower / __str_unicode_upper

ASCII + Unicode-aware case mapping.

__str_replace_subrange / __str_remove_range / __str_insert

Mutating range edits.

__str_drop_first_sub / __str_drop_last_sub / __str_remove_first / __str_remove_last

Dropping front/back chunks.

__str_from_int / __str_from_double / __str_from_bool / __str_from_int_radix

Numeric / Bool to string conversion.

__str_interp

String interpolation glue ("\\(value)").

__str_char_at / __str_codepoint_at / __str_codepoint_len

Character + scalar indexing.

__str_sorted / __str_shuffled / __str_min / __str_max

Sequence ops via Character ordering.

__str_reserve_capacity / __str_pop_last / __str_remove_at

Storage + mutation primitives.

__str_make_iterator / __str_enumerated

Iteration support — for-in, .enumerated().

__str_random_element

Picks a random Character.

Array — array_rt.c39 functions

__array_create / __array_create_n / __array_create_repeat

Empty, capacity-hint, repeat-element constructors.

__array_append / __array_insert / __array_concat / __array_plus

Mutation + concatenation.

__array_get / __array_get_ptr / __array_get_str / __array_len

Indexed access + count.

__array_remove_at / __array_remove_first / __array_remove_last / __array_pop_last

Element removal at index / ends.

__array_clear / __array_clear_discarding_capacity

Reset all / reset + free storage.

__array_first / __array_last / __array_first_index / __array_last_index

End access + lookup index.

__array_contains / __array_elements_equal

Predicate searches + equality.

__array_lex_precedes / __array_starts_with

Lex compare + prefix check.

__array_clone / __array_capacity / __array_grow

COW clone + capacity introspection.

__array_print

Pretty-print into a string buffer.

__array_make_iterator

for-in support.

Dictionary — dict_rt.c30 functions

__dict_create / __dict_create_sized / __dict_create_unique_keys

Empty, capacity-hinted, literal constructors.

__dict_get / __dict_set / __dict_remove / __dict_contains

Subscript + membership.

__dict_index_for_key / __dict_first / __dict_random_element

Index resolution + first / random pick.

__dict_count / __dict_capacity / __dict_eq

Size + equality.

__dict_keys / __dict_keys_array / __dict_values_array

Materialise key/value views as arrays.

__dict_iter / __dict_iter_next / __dict_make_iterator

for-in over key/value pairs.

__dict_merging / __dict_get_or_create_arr / __dict_reserve

Merge with strategy + reserve / multi-value upserts.

__dict_description / __dict_clear / __dict_free

Pretty-print + reset / free.

Set — set_rt.c33 functions

__set_create / __set_create_str

Constructors (typed + string fast path).

__set_insert / __set_insert_i / __set_remove / __set_remove_first / __set_remove_all / __set_update_with

Mutation primitives.

__set_contains / __set_count / __set_capacity / __set_underestimated_count

Membership + size queries.

__set_union / __set_intersection / __set_subtracting / __set_symmetric_difference

Set algebra.

__set_is_subset / __set_is_superset / __set_is_strict_subset / __set_is_strict_superset / __set_is_disjoint

Containment predicates.

__set_filter / __set_map / __set_sorted / __set_shuffled

Higher-order ops + ordered views.

__set_min / __set_max / __set_first_index / __set_first_ptr / __set_get_ptr / __set_random_element

Element access.

__set_reserve / __set_description

Capacity + pretty-print.

Math — math_rt.c15 functions

__math_sin / __math_cos / __math_tan

Trig functions (radians).

__math_asin / __math_acos / __math_atan / __math_atan2

Inverse trig + 2-arg atan2.

__math_sinh / __math_cosh / __math_tanh

Hyperbolic trig.

__math_exp / __math_pow

Exponential + power.

__math_log / __math_log2 / __math_log10

Natural / base-2 / base-10 logarithm.

__swift_max_f64 / __swift_min_f64 / __swift_abs_f64 / __swift_abs_i64

min/max/abs intrinsics for Double + Int.

Concurrency — async_rt.c11 functions

__swift_task_create / __swift_task_run / __swift_task_free / __swift_task_result / __swift_task_await

Task lifecycle for async/await.

__swift_taskgroup_create / __swift_taskgroup_add / __swift_taskgroup_await_all / __swift_taskgroup_free

Structured concurrency via TaskGroup.

__swift_async_return / __swift_main_actor_run

Async return convention + main-actor entry.

Actor isolation — actor_rt.c5 functions

__actor_create / __actor_destroy / __actor_acquire / __actor_release / __actor_enqueue / __actor_is_isolated / __main_actor_run

Single-thread WASM model — actors serialise via a per-actor queue, no real preemption.

Reference counting — arc_runtime.c8 functions

__miniswift_alloc / __miniswift_retain / __miniswift_release / __miniswift_refcount / __miniswift_is_uniquely_referenced

Class instance ARC, COW eligibility.

__atomic_fetch_add / __atomic_fetch_sub

Atomic primitives (single-thread WASM = ordinary loads).

Existentials & Any — any_rt.c7 functions

__any_box_int / __any_box_double / __any_box_bool / __any_box_ptr

Box primitives + objects into existential.

__any_as_int / __any_as_ptr / __any_get_tag

Unbox + introspect tag.

IR Lowering

Compile-time handlers that map Swift method calls to IR. Each file in modules/stdlib/ir_lowering/ handles one type-family.

array.c

Array.append / map / filter / reduce / sorted / contains / first(where:) / lastIndex(of:) → array_rt calls.

string.c

String.split / lowercased / uppercased / hasPrefix / replacingOccurrences / interpolation → string_rt calls.

dict.c

Dictionary subscript / merge / mapValues / filter / removeAll → dict_rt calls.

set.c

Set membership, set algebra (∪ ∩ ∖ △), predicates → set_rt calls.

numeric.c

BinaryInteger / BinaryFloatingPoint method calls — distance(to:), advanced(by:), magnitude.

conv.c

Int(_:), Double(_:), String(_:radix:) — numeric & textual conversions.

seq.c

Sequence / Collection generic ops — for-in, makeIterator, indices.

init.c

Initializer dispatch (9 entries) — handles both default and memberwise inits.

global_math.c

Free-standing math — abs, max, min, swap.

calendar.c / data.c / result.c

Calendar, Data, Result method dispatch.

Known Limitations

Type registry is broad; runtime depth varies. The list below names the gaps that bite most.

Int128 / UInt128 / Float80

Registered but arithmetic ops use 64-bit fallback. Wide-int multiply / divide unimplemented.

Float16

No native WASM half precision; all ops widen to Double.

Decimal

Type slot only — high-precision decimal arithmetic isn't shipped.

Codable runtime

Encodable / Decodable conformances aren't auto-synthesised; relies on Foundation JSON bridge for primitive cases.

Mirror / runtime reflection

Mirror struct registered; introspection is shallow (no children walking).

UnsafePointer family

Pointer arithmetic basic; bound-memory rebinding + memcpy primitives not yet wired.

Sendable enforcement

Marker recognised; data-race static checking is best-effort.

String regex

Regex literals + string.matches(of:) not yet lowered.

Async sequences

AsyncSequence / AsyncStream protocols registered; iterator runtime stubs only.

Distributed actors

Distributed module not in scope.

Macros

No macro expansion plugin host — @Observable, #stringify, etc. parse but don't expand.

UTF8Span ops

Type registered for Swift 6 forward-compat; span-based methods limited.

Standard Library — What's Implemented

Type Registry

Runtime Functions

IR Lowering

array.c

string.c

dict.c

set.c

numeric.c

conv.c

seq.c

init.c

global_math.c

calendar.c / data.c / result.c

Known Limitations

Int128 / UInt128 / Float80

Float16

Decimal

Codable runtime

Mirror / runtime reflection

UnsafePointer family

Sendable enforcement

String regex

Async sequences

Distributed actors

Macros

UTF8Span ops