🚀 Features

• (beam) Support Erlang/BEAM target in standalone compiler (#4644) (30310e4)

🐞 Bug Fixes

• (beam) Collapse array-literal process-dict ref round-trips in FFI/Emit calls (#4626) (234ee08)
• (beam) Make Emit $N substitution a single left-to-right pass (#4631) (48af8db)
• (js/ts) Throw an error when trying to set non-property memeber inside of jsOptions (#4624) (2d9673f)
• (js/ts) Reject JS-permissive date strings that .NET TryParse rejects (#4588) (09003de)
• (js/ts) Make Exception.ToString() return the message instead of "Exception" (#4635) (4c36f76)
• (python) Avoid union case field name collision with Union.name (#4647) (ff5df24)
• (python) Make [] union static members work (#4634) (#4636) (15eb83e)

View changes on Github

🚀 Features

• (js/ts/python) Add missing standard DateTime format specifiers for JS/TS and Python (#4547) (90f5eb7)
• (js/ts/python) Add missing StringBuilder.Append overloads for numeric types (#4568) (b402c30)

🐞 Bug Fixes

• Check MSBuild exit code instead of stderr for project cracker failure detection (#4564) (914a616)
• [JS/TS] Fix DatetimeOffset.ToString("s") (#4596) (3ce6f3f)
• [Rust] Update hashing and datetime tests (#4613) (9d39037)
• (all) Duplicate LetRec bindings during inline expansion (#4592) (62612a5)
• (all) Forward --pathmap: option to FCS so CallerFilePath respects (PathMap) (#4585) (764c383)
• (all) Fix super call in multi-level generic class hierarchy using wrong mangled name (#4414) (db1d4d2)
• (beam) Handle string binaries in Seq enumerator (#4591) (6e78058)
• (js/ts) Fix JSX props with long string values causing compile error (fixes #3839) (#4545) (d828a46)
• (js/ts) Fix datetime custom format off by one year (#4558) (83bdbb5)
• (js/ts) Hex format specifier uses no padding unless precision is specified (#4603) (ba9857a)
• (js/ts) Fix Decimal.GetBits returning incorrect mantissa after round arithmetic result (#4561) (345bcd4)
• (js/ts) Fix G/g format specifier corrupting exponential notation when trimming trailing zeros (#4587) (773c098)
• (js/ts) Add support for match clauses in JSX.create (#4620) (616edca)
• (js/ts) Don't spread last arg in String.Concat call (#4621) (3de580e)
• (js/ts) Inline AttachMembers members at call sites (#4622) (63bcd3d)
• (js/ts/python) Fix FSharpOption not recognized as union type in F# reflection (#4529) (d78a37d)
• (python) Fix regex lookbehind patterns being incorrectly converted (#4560) (4ce5cd7)
• (python) Avoid duplicate captured argument in hoisted guards (#4610) (#4611) (90aec48)
• (ts) Enforce browser-only compatibility in fable-library-ts tsconfig (#4563) (10c81c1)

View changes on Github

Fixed

• [Python] Fix derived classes of generic abstract classes not being instantiable due to mismatched mangled method names between abstract stubs and overrides (by @dbrattli)
• [Dart/Rust] Fix ResizeArray reference equality (by @ncave)
• [JS/TS/Python/Beam] Fix ResizeArray (System.Collections.Generic.List) equality to use reference equality instead of structural equality (fixes #3718)
• [Beam] Fix List.Cons call replacement and test (by @ncave)
• [Beam/Dart/Python/TypeScript] Fix Array.Equals to use reference equality instead of structural equality (by @ncave)
• [Dart/Python/TypeScript/Rust] Fix Seq.foldBack2 for sequences with different lengths (by @ncave)
• [All] Fix missing HashSet implementations and tests (by @ncave)
• [Rust] Fix Array/HashMap/HashSet internal representation (by @ncave)
• [Rust] Fix F# classes reference equality semantics (by @ncave)
• [Python] Fix missing Array module implementations and tests (by @ncave)
• [Python] Fix object expressions implementing interfaces with [<CLIEvent>] members no longer produce unimplementable abstract Protocol members (fixes #3039)
• [Python] Fix DateTime.TryParse incorrectly assigning DateTimeKind.Local to naive datetime strings (should be DateTimeKind.Unspecified) (fixes #3654)
• [JS/TS] Fix String.Contains ignoring StringComparison argument (second argument was silently discarded)
• [Python] Fix String.Contains ignoring StringComparison argument (second argument was silently discarded)
• [All] Fix --noRestore not skipping MSBuildCracker restores (by @ randrag)

Contributors

• @ncave
• @dbrattli

Added

• [Python/Beam] Add F# quotation support — construction, pattern matching, and evaluation via LeafExpressionConverter.EvaluateQuotation (by @dbrattli)
• [JS/TS] Add F# quotation support — construction, pattern matching, and evaluation (by @OnurGumus)
• [All] Add support for Guid.CreateVersion7() and Guid.CreateVersion7(DateTimeOffset) (by @OnurGumus)
• [All] Add missing Array, List, and Seq random choice/shuffle/sample members and tests (by @ncave)
• [Dart/Rust] Add missing System.Random implementations and tests (by @ncave)
• [Beam] Implement missing DateTimeOffset members, add DateOnly and TimeOnly support (by @dbrattli)

Fixed

• [All] Fix unnecessary object allocations during AST traversal when visiting Import expressions (by Repo Assist)
• [Beam] Fix System.Random.Next(0) implementation (by @ncave)
• [Python] Fix System.Random seeded implementation (by @ncave)
• [Beam] Fix System.Random seeded implementation to use per-instance state (by @dbrattli)
• [Dart] Fix Array.compareWith comparing lengths before elements, producing wrong results for arrays with common prefixes (fixes #2961)
• [Python] Fix unsafe option unwrapping in DateTimeOffset.get_Offset and regex replacements (by @dbrattli)
• [All] Replace unsafe option .Value unwrapping with safe alternatives in Python/Replacements.fs and Rust/Fable2Rust.fs (code scanning alerts IONIDE-006)
• [All] Add [<return: Struct>] to partial active patterns in Dart and Rust targets to reduce allocations (code scanning alerts IONIDE-009)
• [JS/TS] Fix Guid to use cryptographically strong random values (by @ncave)
• [Python] Fix DateTimeOffset millisecond constructor and property (by @ncave)
• [Python] Implement missing DateTimeOffset members and fix equality/comparison to use UTC-normalized instants (by @dbrattli)
• [Python] Add DateOnly and TimeOnly support (by @dbrattli)
• [Python] Fix String.IndexOf/LastIndexOf with StringComparison argument emitting it as a start-index instead of a compile error (by @repo-assist)
• [Beam] Fix String.IndexOf/LastIndexOf with StringComparison argument incorrectly treating the enum value as a start index
• [JS/TS/Python] Fix Async.StartChild with timeout always timing out even when the computation finishes before the deadline (fixes #4481) (by @MangelMaxime)

Contributors

• @ncave
• @dbrattli
• @OnurGumus
• @MangelMaxime

Fixed

• [Dart] Enable explicit variable typing for more data types (by @ncave)
• [Dart] Fix tests for round, sign, truncate, log, log2, log10, pow, DivRem, Min, Max, Clamp, MinMagnitude, MaxMagnitude, cosh, sinh, tanh, and float Parse (by @ncave)
• [Python] Add Math.DivRem support for int, int64, and bigint (by @dbrattli)
• [Python] Fix modulo with negative numbers using Python floored semantics instead of .NET truncated semantics for bigint (fixes #4462) (by @dbrattli)
• [Beam] Fix System.String.Concat with 4+ arguments not being supported (by @dbrattli)
• [TS/Python] Fix thisArg type for overloads in structs (#4453) (by @ncave)
• [TS/Python] Fix invalid this argument type in structs (#4453) (by @ncave)
• [JS/TS] Fix N format specifier (ToString("N0"), String.Format("{0:N0}", ...)) producing a trailing dot when precision is 0 (fix #2582) (by @MangelMaxime)
• [JS/TS] Fix C0 and P0 format specifiers producing trailing dot (e.g., "¤1,000." → "¤1,000") (by @MangelMaxime)
• [All] Fix captured side-effect-free values (e.g. empty ResizeArray) being incorrectly inlined into object expression getters in release mode, causing a new instance to be created on each getter call (fixes #3779) (by @MangelMaxime)
• [Python] Fix missing await on else branch of ternary expressions in async closures (by @dbrattli)
• [Beam] Fix |> ignore on cross-module Emit calls generating variable bindings that shadow Emit case-clause variables (by @dbrattli)
• [Beam] Fix containsIdentRef not checking Call ThisArg (by @dbrattli)
• [All] Fix CLI color not resetting after error messages (fixes #3755) (by @MangelMaxime)
• [JS/TS] StringEnum now respect CompiledValue and CompiledName (by @shayanhabibi)
• [JS/TS] Fix invalid syntax emitted when negating negative literals (fix #4251) (by @MangelMaxime)
• [Rust] Fix negative counting in CallInfo.GenericArgs (by @ncave)
• [Rust] Fix inline bindings and captured idents tracking (by @ncave)
• [Rust] Fix return! in async computation expressions so inner async workflows are returned and awaited correctly (by @mizzle-mo)
• [JS/TS] Improve Regex.Escape and Regex.Unescape handling (by @MangelMaxime)
• [All] Fix allow plugins to target .NET6 target framework (by @MangelMaxime)
• [Python] Fix function references passed as arguments inside tail-call optimised functions gaining unnecessary default parameters for outer TCO variables they don't reference (fix #3877)
• [TS] Fix abstract instance methods not emitted in TypeScript when class uses [<AttachMembers>] (fixes #3506) (by @MangelMaxime)
• [JS/TS] Fix Unchecked.defaultof<'T> for struct types with fields returning undefined instead of zero-initialized values (by @MangelMaxime)
• [JS/TS] Fixed quotation for union string cases (by @MangelMaxime)
• [Python] Fix Unchecked.defaultof<'T> for struct types with fields returning incorrect values instead of zero-initialized instances (by @MangelMaxime)
• [Python] Fix Unchecked.defaultof<char> returning "" (empty string) instead of "\u0000" (null character) (by @MangelMaxime)
• [Python] Improve Unchecked.defaultof<_> for declared entities (by @MangelMaxime)

Contributors

• @ncave
• @dbrattli
• @MangelMaxime
• @mizzle-mo
• @shayanhabibi

Added

[All] Add support for [<InlineIfLambda>] (by @MangelMaxime)

Contributors

• @MangelMaxime

Fixed

• [JS/TS] Fix Array.zeroCreate producing null for user-defined struct (value type) elements instead of a default-initialized instance (by @MangelMaxime)
• [All] Fix interpolated string holes missing format specifiers in State.fs and Python/Replacements.fs (code scanning alerts 1144, 1145, 1512)
• [Rust] Replace unsafe .IsSome && .Value option pattern with Option.exists in Fable2Rust.fs (code scanning alert 1125)
• [JS/TS] Fix Unchecked.defaultof<char> being emitted as null instead of '0円' (by @MangelMaxime)
• [JS/TS] Fix static val mutable fields declared with [<DefaultValue>] not being zero-initialized (fix #2739) (by @MangelMaxime)
• [JS/TS/Python] Fix record/struct types augmented with static let or static member val generating extra constructor parameters for each static field, causing constructor arguments to be assigned to wrong slots (by @MangelMaxime)
• [TS] Annotate System.Collections.Generic.IList<T> as MutableArray<T> (by @MangelMaxime)
• [JS/TS] Fix ResizeArray index getter/setter not throwing IndexOutOfRangeException when index is out of bounds (fix #3812) (by @MangelMaxime)
• [Beam] Fix unused term warning in try/catch when exception variable is not referenced (by @dbrattli)
• [Beam] Fix "no effect" warning for pure BIF calls (self/0, node/0) in non-final block positions (by @dbrattli)
• [Beam] Fix reraise() generating unbound MatchValue variable — use raw Erlang reason variable for re-throw (by @dbrattli)
• [Beam] Fix Erlang.receive<'T>() resolving to timeout overload due to F# unit argument (by @dbrattli)
• [JS/TS] Generate comments for members in class decorated with [<AttachMembers>] (by @MangelMaxime)
• [Beam] Fix [<ImportAll>] generating invalid module:*() Erlang code when binding is used as a value (by @dbrattli)
• [Beam] Fix string slicing and Substring with compound expressions producing wrong binary:part length due to missing parentheses in emitted Erlang (by @dbrattli)
• [Beam] Fix non-ASCII characters in string literals being truncated to single bytes — emit <<"..."/utf8>> instead of <<"...">> (by @dbrattli)
• [Beam] Fix Emit expressions with case leaking variables into surrounding scope — auto-wrap in IIFE for scope isolation (by @dbrattli)

Contributors

• @dbrattli
• @MangelMaxime

Added

• [Beam] Auto-generate rebar3 scaffold (rebar.config, .app.src) after compilation; .erl files now placed in src/ subdirectories (by @dbrattli)
• [Beam] Support [<ImportAll>] + [<Erase>] interface pattern for typed FFI bindings (by @dbrattli)

Fixed

• [Beam] Fix dropped top-level side effects — multiple ActionDeclaration main/0 functions are now merged (by @dbrattli)
• [Beam] Fix %% escape in string interpolation producing double % instead of single (by @dbrattli)
• [Beam] Fix double-quoted atoms for uppercase CompiledName on DU cases (e.g. ''EXIT'' → 'EXIT') (by @dbrattli)
• [Beam] Fix cross-project imports producing self-recursive calls when source files share the same name (by @dbrattli)
• [Beam] Support Type.GetGenericArguments and Type.GetInterface for reflection (by @dbrattli)
• [TS] Correctly resolve type references for TypeScriptTaggedUnion (by @MangelMaxime and @jrwone0)
• [TS] Expose optional stack property on Exception (by @MangelMaxime)
• [Python] Fix nonlocal/global declarations generated inside match/case bodies causing SyntaxError (by @dbrattli)
• [Python] Fix exception variable captured in deferred closures causing NameError (PEP 3110 scoping) (by @dbrattli)
• [JS/TS] Support format specifiers and single hole in JSX string templates (by @MangelMaxime)
• [All] Fix generic parameter resolution in inline functions with static member constraints (by @Programmerino and @MangelMaxime)

Contributors

• @dbrattli
• @MangelMaxime
• @Programmerino
• @jrwone0

Added

• [Beam] Add arithmetic tests and support for DivRem, MinMagnitude, MaxMagnitude, Decimal rounding, BigInt.Log (by @dbrattli)
• [Beam] Add fable_random.erl and fix Random seeded/NextBytes tests (by @dbrattli)

Fixed

• [Python] Fix __hash__ to return native int instead of int32 for Python 3.14 compatibility (by @dbrattli)
• [Python] Fix PyPI publish workflow version pattern to support rc tags (by @dbrattli)
• [Beam] Bundle fable-library-beam in NuGet package so dotnet fable --lang beam works (by @dbrattli)
• [Beam] Fix optional arguments by unwrapping at call sites and padding missing trailing args (by @dbrattli)
• [Beam] Fix generic constraint interface dispatch (by @dbrattli)
• [Beam] Fix class constructor field invokes and explicit val fields (by @dbrattli)
• [Beam] Fix mutable record field mutation (by @dbrattli)
• [JS/TS] Allows compiling fable-library-ts for Browser environment (by @goswinr)

Contributors

• @dbrattli
• @goswinr

Added

• [Beam] Add Erlang/BEAM target (--lang beam). Compiles F# to .erl source files. 2086 tests passing. (by @dbrattli)

Fixed

• [Python] Fix type var scoping for PEP 695 annotations: emit Any for type vars outside function scope and prevent non-repeated generic params from leaking into ScopedTypeParams (by @dbrattli)
• [JS/TS] Ignore extra args in FSharpType functions (by @olivercoad)

Contributors

• @dbrattli
• @olivercoad