Changelog

September 12, 2026 · View on GitHub

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

5.17.1 - 2026-09-11

🐞 Bug Fixes

(js/ts) Keep the sign of negative decimals below 0.1 (91d80f18)
(js/ts) Respect the precision when formatting decimals below 0.1 (1c02557e)
(js/ts) Omit the decimal sign when the rounded result is zero (ef63087d)
(python) Preserve record field names in structured formatting (#4952) (fbc162d6)
(python) Support bytes() on generic and bool arrays (#4961) (94b59294)
(python) Parse uint64 values above Int64.MaxValue (584d8ce4)
(python) Report DateTimeKind.Utc for DateTime.UtcNow (4abf06ea)
(python) Reflect an erased union as the type it erases to (0f564c74)
(python) Implement Decimal.GetBits and the bits constructors (cf0c9305)
(python) Round a float to .NET's precision when converting to decimal (4a441b19)
(ts) Declare the type parameter of a flexible-type overload (6f1f1b8a)

View changes on Github

5.17.0 - 2026-09-08

🚀 Features

Add Temporal dates and times (opt-in) (#4759) (3e8f56f7)

🐞 Bug Fixes

(js/ts) Match .NET for G, E and custom numeric formats (6fb03090)
(js/ts) Allow the E format specifier on Int64 and UInt64 (c49d1ec5)
(python) Build typed arrays from lists and sequences (#4944) (5af37779)
(rust) Fix IEnumerable casting, interop and type testing (#4946) (93c2df5b)
(rust) Restore missing bindings (#4947) (2fb46a26)
(ts) Declare local function type params only reachable via constraints (#4943) (8aa6d3b9)
(ts/python) Erase byref from struct copy-and-update locals (#4945) (19a6522e)

View changes on Github

5.16.0 - 2026-09-03

🚀 Features

(all) Quotations: DerivedPatterns, and captured locals as Value nodes (#4919) (fae5093f)
(python) Support quotation derived patterns (#4928) (f6d939a1)
(rust) Observables, Events and IEnumerable (PR 6 of 7 Rust improvements) (#4789) (20175eea)
(rust) System.Uri (PR 7 of 7 Rust improvements) (#4790) (8a551bc9)

🐞 Bug Fixes

Preserve project FSharp.Core reference (#4924) (1289360a)
Report Fable's own logs from the Fable.Compiler API (#4923) (0775c604)
(all) Emit instance calls for virtual methods inherited from Object (#4926) (2fb535a7)
(all) Allow private inline functions to use private values (#4915) (b0740ba9)
(python) Emit Python names for float32 specials (#4938) (b4c45a93)
(python) Compare nested options of different depth (#4940) (5afa2948)
(rust) Observables and Events cleanup (#4908) (ca165045)
(rust) Support string on a tuple (#4916) (510c8a43)
(rust) Decimal culture overloads, and mutables assigned in try/finally (#4918) (58402471)
(rust) Let a string be enumerated (#4921) (395c152b)
(rust) Async perf: stop the async runtime sleeping, and add Parallel (#4920) (88135b90)
(rust) F# exceptions, non-exhaustive matches and obj type tests (#4917) (28da1d76)
(rust) Wait for the other files instead of sleeping before the last one. (#4927) (d329a823)
(rust) Cleanup AsyncBuilder and TaskBuilder (#4936) (3e6bc9bd)
(rust) Fix interface casting, move reflection into declarations (#4939) (04299157)
(rust) Support reflection for no_std (#4941) (bf694309)

View changes on Github

5.15.0 - 2026-08-25

🚀 Features

(standalone) Publish the Fable version the bundle was built from (#4905) (b517d52d)

🐞 Bug Fixes

(all) Find a core entity recorded under a facade assembly (#4903) (60210b86)

View changes on Github

5.14.0 - 2026-08-25

🏗️ Breaking changes

(standalone) Reference a precompiled library (#4900) (90359c31)

🚀 Features

(python) Represent Int32 and Float64 as plain Python int and float (#4856) (ca361ea3)

🐞 Bug Fixes

(all) Invalidate cached project options when inputs change (#4879) (aea3735b)
(all) Error on member reference from a source-less dll (#4894) (065a88d8)
(all) Match entity refs across the precompiled boundary (#4895) (96783631)
(all) Say why an inline member's body could not be found (#4901) (e5b0488e)
(beam) Escape quotes and backslashes in quoted atoms (#4866) (5d5231b3)
(beam) Compile [] cases to atoms instead of binaries (#4867) (366919a7)
(beam) Parse ISO-8601 numeric zone offsets and compare dates by instant (#4868) (bb3c86d7)
(python) Keep original F# field names in record reflection (#4852) (90c1798b)
(python) Stop shipping build artifacts and ship the PEP 561 marker (#4857) (03d40c97)
(python) Derive DateTime "O" format from the value, not the host timezone (#4869) (b3ec8b67)

⚡ Performance Improvements

(python) Back int64 arrays with typed storage (#4864) (78a5d479)
(python) Hash numbers without the safeHash detour (#4865) (32b42b2a)
(python) Elide int32 normalizations that cannot change their argument (#4859) (7e9cd96a)

View changes on Github

5.13.0 - 2026-07-24

🐞 Bug Fixes

(all) Eliminate dead bindings left by CE/inline lowering (#4837) (9f694e97)
(beam) Make reflection metadata agree with record/union codegen (#4849) (ec6a3df0)
(js/ts) Resolve generic params when reflecting erased union fields (#4851) (619d7afd)
(js/ts,python) Inline Option/ValueOption combinators to avoid closures and allocations (#4836) (61cac646)
(python) Honor custom Equals and GetHashCode in structural values (#4850) (22ec1919)

⚡ Performance Improvements

(all) Lower constant ±1 step ranges to counted for-loops (#4838) (ab28daec)

View changes on Github

5.12.0 - 2026-07-22

🚀 Features

(beam) Render %A in F# syntax instead of dumping Erlang terms (#4814) (218e0c40)

🐞 Bug Fixes

(beam) Correct char-to-string conversion and console Unicode encoding (#4812) (df8e01d6)
(beam) Isolate each top-level effect's variables in main/0 (#4815) (8d708633)
(beam) Write package modules to the package's own src/ (#4817) (06bf863c)
(beam) Implement Async.AwaitTask (#4819) (17cc3b6a)
(beam) Keep the original stacktrace when an async error is re-raised (#4818) (d7afa278)
(beam) Decode UTF-8 codepoints in ToCharArray and related String functions (b2ce3067)
(python) Avoid UTF-8 boundary panic in integer parsing (#4825) (8243a711)
(python) Detect radix prefix after whitespace and sign (#4828) (5ab1382b)

View changes on Github

5.11.0 - 2026-07-17

🚀 Features

(dart) Quotations (#4784) (019a6ade)

🐞 Bug Fixes

(python) Don't emit too many leading dots for relative imports of nested files (#4803) (9fa49244)
(python) Make union case classes hashable again (#4805) (63b80138)
(python) Make class declarations and references agree on type names (#4807) (ae4b910b)

View changes on Github

5.10.0 - 2026-07-16

🚀 Features

(beam) Support Environment.CurrentDirectory and GetEnvironmentVariable (#4801) (55b9d560)
(beam) Support setting Environment.CurrentDirectory (#4783) (7b2a262f)
(rust) Various codegen and runtime improvements (#4781) (ae10cd2c)
- Cast bool to integer types; support ** via .powf
- Add Decimal.IsInteger/IsEvenInteger/IsOddInteger/IsCanonical
- Fix two-switch decision trees dispatching to the wrong target
- Fix reference-typed match bindings panicking via mem::zeroed
- Fix string and non-ident option pattern matches emitting invalid Rust match arms
- Fix Convert.ToXxx(bool)
- Fix Char.ToUpper/ToLower truncating multi-char case mappings
- Fix Random.nextDouble panic message
- Fix Map.find/tryFind panicking on reference-typed values

🐞 Bug Fixes

(all) Skip translating unreachable branch of constant-condition if/then/else (#4799) (53c06de1)
(python) Make the assert_not_equal failure message describe the failure (#4778) (721fb437)

View changes on Github

5.9.0 - 2026-07-15

🚀 Features

(js/ts) Add System.IO.Directory support (Exists, CreateDirectory) (#4798) (6568f35e)
(js/ts/python/beam) Preserve member calls and pattern matches in quotations (#4780) (55482e6b)

🐞 Bug Fixes

(beam) Make Assert.AreEqual/NotEqual raise, and stop emitting reflection calls for erased types (#4775) (d9711d4c)

View changes on Github

5.8.1 - 2026-07-13

🐞 Bug Fixes

(beam) Make F# reflection work on the Beam target (#4766) (b15b280d)
(beam) Give sized integers .NET fixed-width semantics (#4769) (2ed39630)
(beam) Qualify Erlang module names by their OTP app (#4770) (5516c8d8)
(beam) Entry point argv and exit code, bigint from float, option reflection (#4772) (ea915541)

View changes on Github

5.8.0 - 2026-07-11

🚀 Features

(beam) Implement Async.StartChild in fable_async runtime (#4760) (eb2ad9a4)

🐞 Bug Fixes

(beam) Order discriminated union comparison by declaration order (#4761) (3597a582)
(beam) Preserve function-value identity for PhysicalEquality (#4762) (727673f3)
(js/ts) Don't drop unsupported jsOptions statements when inlining as POJO (#4754) (4cbc44fc)
(js/ts) Async cancellation propagation and continuation double-resolve (#4746) (c78a9a8e)
(js/ts) Date arithmetic: PM parsing, AddMonths day clamp, AddYears offset (#4744) (be0558eb)
(js/ts) Int64 non-decimal parsing and BitConverter .NET mismatches (#4748) (2704d9c5)
(python) Propagate [] return value as process exit code (#4763) (a8d9bf5f)

⚡ Performance Improvements

(python) Avoid conversion-dunder hop in numeric fast paths (#4756) (838eda53)
(python) Speed up array aggregates and generic storage in fable-library-core (#4755) (e40a7dc4)

View changes on Github

5.7.0 - 2026-07-09

🚀 Features

Add --noGitignore flag to skip generating fable_modules/.gitignore (#4730) (3742b950)

🐞 Bug Fixes

MailboxProcessor dropping falsy messages and unit replies (8299b2e7)
(all) Include original exception message when loading a Fable plugin fails (#4739) (659e73a4)
(all) Add Seq.enumerateTryWith for try/with in seq, list, array comprehensions (#4750) (448c90d7)
(beam) EndsWith regression for empty pattern with non-ordinal comparison (eee2ad3f)
(js/ts) Represent union cases with no fields as singletons (3f6e618e)
(js/ts) Match .NET NaN semantics in JS comparison, min and max (7e5106f9)
(js/ts) BigInteger byte-array corruption, checked conversions, gcd, log2 (#4743) (f3cb7f2b)
(js/ts) Observable/Event dropping null/undefined/unit values (#4742) (75bff73b)
(js/ts) EndsWith regression for empty pattern with non-ordinal comparison (7793ed7b)
(js/ts/python) Quote strings with the %A format specifier (#4749) (75321f3b)
(python) Accept native floats in fable-library float functions (#4724) (ea4a9853)
(python) Represent union cases with no fields as singletons (0211b4cc)
(python) Emit forward reference for self-referencing static union members (#4752) (452b85f2)
(python) Match .NET NaN and signed-zero semantics in comparison, min and max (383bb93c)
(python) LastIndexOf(value, startIndex) off-by-one on inclusive boundary (bad6bcac)
(python) MailboxProcessor dropping unit replies (8e83ebe3)
(ts/js) Regex.Replace count/substitutions and Regex.Split semantics (#4741) (d6ae6bd3)

⚡ Performance Improvements

(python) Use native operators for int64/uint64 arithmetic (#4727) (f062d668)
(python) Rewrite hot Seq combinators as native Python generators (#4728) (73e0eab9)
(python) Read union case fields directly instead of rebuilding Array (#4725) (e4eaa80b)

View changes on Github

5.6.0 - 2026-07-05

🚀 Features

(all) Allow [<Emit>] on StringEnum cases (#4711) (0b1f61ee)
(js/ts) Optimize printfn with constant string to console.log (#4718) (2d6d083a)
(js/ts) Add Path.Combine support (b1b1e273)
(js/ts) Add System.IO.Path and System.IO.File API support (ec99fac5)
(js/ts/python) Warn on duplicate attached member names (#4715) (fd06aa64)
(js/ts/python) Add Environment and Console.Error support (6e082f95)
(py) Add Path.Combine support (4c901c65)
(python) Add Directory.Exists, Directory.CreateDirectory (f4b4eabc)
(ts) [] interfaces extend parent [] type (#4717) (4f4243cd)

🐞 Bug Fixes

Generate an error on erased union case typed as obj (#4710) (bf2134d5)
(all) Include return type in overload suffix for op_Implicit/op_Explicit (#4712) (a6846010)
(js/ts) DateTime.ToString() and %A are now consistent across all DateTimeKind values (#4714) (de98b0e4)
(python) Accept allowAccessToPrivateRepresentation in FSharpType.IsUnion/IsRecord/GetUnionCases (#4722) (7f915f1d)
(ts) Strip byref annotation from compiler-generated copy-update locals (#4716) (1e072ed2)

⚡ Performance Improvements

Split Fable.Transforms into per-target projects for faster incremental builds (#4720) (260c962f)

View changes on Github

5.5.0 - 2026-06-30

🚀 Features

(all) Add Compiler.is* target detection flags for conditional branching (#4692) (621dea31)
(js/ts) Map task { } to Promise (97f54d36)
(js/ts/python/beam) Add support for Async.AwaitEvent (#4693) (71c98179)

🐞 Bug Fixes

(all) Pass raw value for optional arguments of native bindings (#4688) (a4c75483)
(all) Support .NET format specifiers and alignment in interpolated strings (#4695) (7c50a3af)
(all) Error on inline function referencing private value (#4701) (cea6806e)
(beam) Support module-level mutable variables via process dictionary (#4676) (535b9af0)
(beam) Namespace module-level mutable state keys by module (#4683) (1ec28ab1)
(js) Respect StringComparison in String.IndexOf/LastIndexOf (#4681) (7cb92d52)
(js/ts) Implicit DateTime to DateTimeOffset conversion (#4697) (fcbd9b91)
(js/ts) Int list is not a union type (#4698) (ecbecbe7)
(js/ts) Hoist emitJsStatement imports with trailing comments (#4702) (e820eb72)
(js/ts) Uncurry mutable module value alias calls (#4703) (0de0d218)
(js/ts) Pass TypeInfo to getRecordFields to handle None fields in anonymous records (#4704) (c977d78b)
(js/ts/python) Drop allowAccessToPrivateRepresentation arg from reflection calls (#4689) (ec3cded7)
(python) Fix task while loop stack overflow (fdb0ec37)
(ts) Use declared type-param names in object expression generic methods (#4685) (1c3e7d99)
(ts) Use signature type-param names when implementing generic interface methods (#4686) (03e5deee)
(ts) Bound enum-constrained type parameters with extends number (#4687) (15daf624)
(ts) Widen isEnumDefined value parameter to accept any value (#4690) (0d6498dd)
(ts) Keep enclosing type parameters in scope for nested members (#4691) (f5723a2d)
(ts) Re-declare class type params on generic static attached members (#4696) (2da50780)
(ts) Filter class type params from attached let-binding methods (#4700) (d3a6a1dd)

View changes on Github

5.4.0 - 2026-06-24

🚀 Features

(all) Support Exception.InnerException across all targets (#4677) (c9b3ee24)

🐞 Bug Fixes

(beam) Make immutable class instances process-portable (#4670) (182eebef)

View changes on Github

5.3.0 - 2026-06-16

🚀 Features

(beam) Add !^ erased-cast operator to BeamInterop (#4659) (206776b)

🐞 Bug Fixes

Add type specifiers to interpolated strings (#4646) (512ae4d)
(all) Cli fable clean command crash when output directory doesn't exist (#4651) (de379e8)
(all) Align invalidArg error message with .NET format (#4662) (e672eb7)
(beam) Preserve element type through Option.Value for interface dispatch (#4661) (e5521b6)
(python) Emit wildcard default for union or-patterns (#4649) (#4653) (c96f0ec)

View changes on Github

5.2.0 - 2026-06-10

🚀 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

5.1.0 - 2026-05-28

🚀 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

5.0.0 - 2026-04-21

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)

5.0.0-rc.7 - 2026-04-07

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

[Python] Remove python-dateutil dependency from fable-library; use stdlib datetime.fromisoformat with strptime fallback
[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)

5.0.0-rc.6 - 2026-03-31

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)

5.0.0-rc.5 - 2026-03-20

Added

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

5.0.0-rc.4 - 2026-03-19

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' (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)

5.0.0-rc.3 - 2026-03-10

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)

5.0.0-rc.2 - 2026-03-03

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)

5.0.0-rc.1 - 2026-02-26

Added

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

Fixed

[Beam] Fix object expression self-references, constructor as self patterns, and property get/set key collisions in object expressions (by @dbrattli)
[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)

5.0.0-alpha.24 - 2026-02-13

Fixed

[Python] Fix HashSet operations (Count, Contains, Remove, UnionWith, IntersectWith, ExceptWith) to work with both native Python sets and custom MutableSet (by @dbrattli)
[Python] Fix Array.length, .Length, Array.isEmpty, and ResizeArray.Count to use len() instead of .length property for plain Python list interop (by @dbrattli)
[Python] Fix Task<T> pass-through returns not being awaited in if/else and try/with branches (by @dbrattli)
[Python] Fix :? T as x type test pattern in closures causing UnboundLocalError due to cast() shadowing outer variable (by @dbrattli)
[All] Prevent Fable from freezing when running a sub-process via --run (fix #3631) (by @MangelMaxime)
[All] Improve console width detection when rewritting console output (by @MangelMaxime)

5.0.0-alpha.23 - 2026-02-03

Changed

[Python] Changed DU representation to use separate classes for each case (by @dbrattli)
[Python] Fable will no longer auto-generate __str__ or __hash__ for custom types. Use the Py.Stringable and Py.Hashable marker interfaces to generate these methods (by @dbrattli)

Added

[Python] Added ABC base classes for F# types and Py marker interfaces for Python interop (by @dbrattli)
[Python] Add tuple pattern matching with guards and improve match statement generation (by @dbrattli)
[Python] Add Python 3.10+ match statement support for pattern matching (by @dbrattli)

Fixed

[Python] Fix curry/uncurry to handle arbitrary number of arguments (by @dbrattli)
[Python] Fix type annotations for protocols, Option casting, and abstract classes (by @dbrattli)
[Python] Fix type annotations for curried functions and numeric types (by @dbrattli)
[Python] Fix type annotations for inref, IList, DateKind, and regex collections (by @dbrattli)
[Python] Fix type annotations for protocols, ABCs, Atom, and Set module (by @dbrattli)
[Python] Fix type annotations for async functions, date operations, and None handling (by @dbrattli)
[Python] Fix type annotations for tuple indexing, generic defaults, and reflection (by @dbrattli)
[All] Fix StringBuilder.Chars getter and setter (by @MangelMaxime)

Removed

[All] Remove --legacyCracker flag, MSBuild cracker is now the default and the only cracker supported (by @MangelMaxime)

5.0.0-alpha.22 - 2025-12-26

Fixed

[Python] Use Fable AST for type parameter extraction instead of Python AST heuristics (by @dbrattli)
[Python] Fix library type stubs for parse_int32/64 and from_integer (by @dbrattli)
[Python] Fix missing type parameters on generic methods (by @dbrattli)
[JS/TS] Fix #4305 DateTimeOffset.Now returns wrong time (by @ncave)

5.0.0-alpha.21 - 2025-12-15

Added

[Python] Support catching Python BaseException subclasses (KeyboardInterrupt, SystemExit, GeneratorExit) for Python interop (by @dbrattli)

Changed

[Python] F# task { } expressions now generate Python async def functions (by @dbrattli)
[Python] Generate idiomatic except clauses for typed exception patterns (by @dbrattli)

Fixed

[Python] Fix ResizeArray compatibility with Seq/Array functions (by @dbrattli)
[Python] Fix FSharpList generic type parameter handling for IEnumerable_1 compatibility (by @dbrattli)

5.0.0-alpha.20 - 2025-12-08

Added

[Python] Add Array.skipWhile support (by @dbrattli)
[Python] Add Array.takeWhile support (by @dbrattli)
[Python] Allow IEnumerator_1 as base class to fix typing issues (by @dbrattli)
[Python] Add Pythonic import path syntax for relative imports (.module, ..parent, ...grandparent) (by @dbrattli)
[Python] Add [<Py.DecorateTemplate>] attribute for creating custom decorator attributes (by @dbrattli)
[Python] Add [<Py.ClassAttributesTemplate>] attribute for creating custom class attribute shortcuts (by @dbrattli)
[Python] Add [<Py.DataClass>] as a built-in shorthand for [<Py.ClassAttributes(style = Attributes, init = false)>] (by @dbrattli)

Fixed

[Python] Fix String.Concat spread operator issue in Python transpilation (by @dbrattli)
[Python] Fix regression [<Erase>] on class types not preventing them from being emitted to Python (by @dbrattli)
[Python] Fix regression %A format specifier to output booleans as lowercase true/false (by @dbrattli)
[Python] Fix various bugs in fable-library numeric types and string operations (by @dbrattli)

Changed

[Python] [<Py.Decorate>] now emits decorator strings verbatim and adds importFrom parameter for explicit import control (by @dbrattli)

5.0.0-alpha.19 - 2025-12-04

Fixed

[Python] Fix printf.cont() not applying continuation function when currying (by @dbrattli)

Added

[Python] Add support for [<Py.Decorate>] attribute on methods (previously only worked on classes) (by @dbrattli)
[Python] Add new [<Py.ClassMethod>] attribute to emit @classmethod instead of @staticmethod (by @dbrattli)
[Python] Added support for Pydantic serialization of core numeric and array types (by @dbrattli)

5.0.0-alpha.18 - 2025-12-03

Fixed

[Python] Fix record member method naming (by @dbrattli)
[Python] Fix regression, named arguments not being converted to snake_case (by @dbrattli)
[Python] Fix regression, erased interfaces should not generate code (#4277) (by @dbrattli)

Changed

[Rust] Update fable-library-rust dependencies (by @ncave)
[All] Update TargetFramework to net10.0 (by @ncave)
[All] Update FCS to latest (commit cfda5f6) (by @ncave)

5.0.0-alpha.17 - 2025-11-27

Changed

[Python] fable-library for Python is now distributed via PyPI instead of being bundled in the NuGet package (by @dbrattli)

5.0.0-alpha.16 - 2025-11-25

Fixed

[All] Fix --cwd with quoted paths (by @MangelMaxime)
[All] Fix --legacyCracker flag logic (by @MangelMaxime)
[All] Fix BuildalyzerCracker so it can work on .NET 10 (by @MangelMaxime)

Changed

[All] Invoke MSBuild from Fable current working directory (by @cr3wdayt5p)

5.0.0-alpha.15 - 2025-11-19

Added

[TS] Added support for erasableSyntaxOnly in TypeScript (by @ncave)
[All] Added some default System exception implementations (by @ncave)
[All] Added ofOption/toOption/ofValueOption/toValueOption (by @ncave)
[Python] Added Decorate attribute to add Python decorators to classes (by @dbrattli)
[Python] Added ClassAttributes attribute to control Python class generation (@dbrattli)
[Python] Added support for Python 3.14 (by @dbrattli)

Changed

[JS/TS] Replace the deprecated substr method with slice (by @Thorium)

Fixed

[TS] Fix ObjectExpr tests with multiple interfaces (by @ncave)
[TS] Fix ObjectExpr abstract base constructor type (by @ncave)
[JS/TS] Fix #4240 Missing DateTime constructor (by @ncave)
[PHP] Fix php import extensions (by @MangelMaxime)
[TS] Fix #3973 Typescript imports file extension (by @ncave)
[TS] Fix support for abstract classes and members (by @ncave)
[TS] Fix getters, setters, indexers in interfaces (by @ncave)
[TS] Enable typedArrays flag usage for TypeScript (by @ncave)
[All] Fix #4221 Fable.Type union case arg names (by @ncave)
[All] Erase Nullable Reference Types to inner type (by @ncave)
[Python] Improve Python (e.g. Pydantic) interop (by @dbrattli)
[JS/TS] Fix comparers for non-nullable types (by @ncave)
[Rust] Fix curried object expression getters (by @ncave)
[Rust] Fix compiler-generated generic args (by @ncave)
[All] Fixed #4041 missing unit argument (by @ncave)
[JS/TS/Python] Fixed eq comparer mangling (by @ncave)
[All] Fix all BitConverter return types (by @ncave)
[TS] Don't cast union case types to any (by @ncave)
[JS/TS] Fix Dictionary.ICollection.Remove (by @ncave)
[TS/Dart] Fixed optional parameter types (by @ncave)
[TS] Initialize un-initialized variables (by @ncave)
[JS/TS] Replace Error with Exception (by @ncave)
[All] Fix MSBuildResolver to include define when restoring the project (by @MangelMaxime)

5.0.0-alpha.14 - 2025-07-25

Added

[Python] Support for Nullable Reference Types (by @dbrattli)
[JS/TS] Fix #3533: Add directives prologues supports (by @MangelMaxime)
[JS/TS] Support for Nullable Reference Types (by @ncave and @MangelMaxime)
[Rust] Initial support for Nullable Reference Types (by @ncave)

Changed

[Python] Use Python 3.12 type parameter syntax. Deprecate Python 3.10 and 3.11 (by @dbrattli)
[Python] Records now snake-cases all member fields (by @dbrattli)
[Python] Anonymous records now preserves the casing of member fields (by @dbrattli)
[Python] Option type is now Option[T] instead of T | None (by @dbrattli)
[Python] Use uv instead of Poetry for package management (by @dbrattli)
[Python] Fable Library for Python is now partially written in Rust (by @dbrattli)
[All] Improve filewatcher error messages (by @goswinr)

Fixed

[Python] Fixed static properties and are now translated as Python class attributes (by @dbrattli)
[Python] Fixed DateTime with DateTimeKind generates proper enum reference (#3689) (by @dbrattli)
[Python] Fixed Dictionary KeyValuePair enumeration when casting to IEnumerable (#3771) (by @dbrattli)
[Python] Fixed createEmpty<T> for interfaces using SimpleNamespace with type casting (#3604) (by @dbrattli)
[Python] Fixed EmitMethod + ParamObject losing keyword arguments (#3871) (by @dbrattli)
[Python] Fixed EmitConstructor + ParamObject losing keyword arguments (#3871) (by @dbrattli)
[Python] Fixed DateTimeOffset.TryParse, ToString() and Offset property access (#3854) (by @dbrattli)
[Python] Fixed anonymous records in Maps causing comparison errors (#3869) (by @dbrattli)
[Python] Fixed handling of erased types for Python (#3968) (by @dbrattli)
[Python] Fixed unit function (zero arguments functions) are transpiled inconsistently (#4126) (by @dbrattli)
[Python] Fixed resource managers with empty body (#3912) (by @dbrattli)
[Python] Fixed Async.Sleepto handle TimeSpan correctly (#4137) (by @dbrattli)
[Python] Make sure snake-cased Record do not conflict (by @dbrattli)
[Python] Do not return None | None for optional unit types (#4127) (by @dbrattli)
[JS/TS] JSX : Alias empty CEs list to null when encountered in the children list (by @MangelMaxime)
[JS/TS] JSX : Allow usage of unbox when definining properties for JSX.create (by @MangelMaxime)

5.0.0-alpha.13 - 2025-05-04

Fixed

[Python] Fixed testing with interfaces leads to incorrect pattern match (#3972) (by @dbrattli)
[Python] Fixed error when type contains multiple generic type parameters (#3986) (by @dbrattli)
[Python] Fixed import path handling for libraries (#4088) (by @dbrattli)
[Python] Reenable type aliasing for imports with name "*" (by @freymauer)
[JS/TS] Optimise JSX output in order to avoid F# list CEs to surface in it (by @MangelMaxime)

Removed

[All] Remove unused Fable.Core copy types from internal module (by @MangelMaxime)

5.0.0-alpha.12 - 2025-03-14

Added

[Python] Add support for nullArgCheck(by @MangelMaxime)
[All] Add support for F# nullness (by @MangelMaxime)
[JS/TS] Add support for Unchecked.nonNull (by @MangelMaxime)
[All] Add support for TreatWarningsAsErrors (by @MangelMaxime)
[All] Print help message on unexpected arguments (by @MangelMaxime)

Fixed

[JS/TS] Make nullArgCheck report the same error message as on .NET (by @MangelMaxime)
[TS] Sanitize DUs case names when generating constructor function (by @MangelMaxime)
[All] Don't print help message on failed compilation (by @MangelMaxime)
[JS] Don't generate an import statement for pojos defined in another file (by @shayanhabibi)

5.0.0-alpha.11 - 2025-03-03

Added

[JS/TS] Add support for CaseRules.LowerAll on StringEnums (by @shayanhabibi)
[Rust] Support Rust 2024 language edition (by @ncave)
[JS/TS] Add C and c format for numeric types (by @MangelMaxime)
[JS/TS] Add B and b format for numeric types (by @MangelMaxime)
[JS/TS] Add n format for numeric types (by @MangelMaxime)
[JS/TS] Generate compiler error when detecting an invalid/unsupported format specifier for numeric types (by @MangelMaxime)

Fixed

[JS/TS] Fix #4025: No reflection info for pojos (by @alfonsogarciacaro)
[JS/TS] Fix #4049: decimal/bigint to integer conversion checks (by @ncave)
[JS/TS] Fix decimal to char conversion checks (by @ManngelMaxime)
[JS/TS] Propagate non-captured exception when running Async.Start or Async.StartImmediate (by @MangelMaxime)
[JS/TS] Report an error at compilation time when trying to use Async.RunSynchronously (by @MangelMaxime)
[JS/TS] Fix short DateTime and DateTimeOffset short format strings (by @MangelMaxime)
[All] Don't scan system packages for plugins (by @MangelMaxime)
[JS/TS] Fix date formatting when repeating a format token more than the known format (example repeating 'd' more than 4 times) (by @MangelMaxime)
[Python] Fix date formatting when repeating a format token more than the known format (example repeating 'd' more than 4 times) (by @MangelMaxime)
[JS/TS] Fix #4010: Supports direct nested types when using jsOptions (by @MangelMaxime)

    let opts =
        jsOptions<Level1> (fun o ->
            o.level2.level3.valueA <- 10
            o.level2.level3.valueB <- 20
            o.topValueA <- 20
        )

[JS/TS] Fix numeric formats (by @MangelMaxime)

Changed

[JS/TS] Throw an error is an invalid Numeric format is provided (mimic .NET behavior) (by @MangelMaxime)

5.0.0-alpha.10 - 2025-02-16

Added

[Python] Print root module and module function comments (by @alfonsogarciacaro)
[Rust] Add support for module comments (by @ncave)
[Rust] Add support for null strings (by @ncave)
[TS/JS] Pojo attribute support (by @alfonsogarciacaro)

Fixed

[JS/TS] - Fix anonymous record printing (#4029) (by @alfonsogarciacaro)
[Python] - Fix #3998: PhysicalEquality (by @alfonsogarciacaro)
[Python] Resolve relative paths for non-qualified imports (#3481) (by @alfonsogarciacaro)
[Python] importSideEffects shouldn't generate identifier (#3965) (by @alfonsogarciacaro)
[JS/TS] Fix #4031: Hoist vars locally in for and while loops (@alfonsogarciacaro)

Changed

[JS/TS] In JSX, generate self closing element when element has no children (#4037) (by @shayanhabibi)

5.0.0-alpha.9 - 2025-01-28

Fixed

[All] Add --realsig+ to fix Method not found: 'Boolean Fable.CompilerOptions.Equals (by @nojaf)

5.0.0-alpha.8 - 2025-01-27

Added

[TS] Include XML Doc comment on interface properties (by @Freymaurer)
[TS] Generate interface type when using the "ParamObject" class pattern (by @MangelMaxime)
[Rust] - Initial support for null values (by @ncave)

5.0.0-alpha.7 - 2025-01-23

Fixed

[All] Disable .NET Welcome message when cracking project (#4014) (by @MangelMaxime)

5.0.0-alpha.6 - 2025-01-23

Added

[All] Add StringBuiler.Append(c: char, repeatCount: int) overload (by @roboz0r)
[All] Added primitive types equality and comparison (by @ncave)
[All] Updated FCS to latest F# 9.0 (by @ncave)
[All] Updated Fable-FCS to latest F# 9.0 (by @ncave)
[All] Updated metadata to latest .NET 9.0 (by @ncave)
[All] Updated FCS type constraints (by @ncave)

Fixed

[Python] Add missing unicode categories in python library (by @joprice)
[All] Log JSON output if we fail to parse MSBuild result (by @MangelMaxime)

5.0.0-alpha.5 - 2025-01-09

Added

[JS/TS/Python] Add new TimeSpan overloads support coming from .NET 9.0 (by @MangelMaxime)
[Rust] Add new TimeSpan overloads support coming from .NET 9.0 (by @ncave)

Fixed

[JS/TS] Fix DateTimeOffset.ToLocalTime (by @MangelMaxime)
[All] Don't fails silently if an unknown argument is provided, instead log the error and print the help message (by @MangelMaxime)

5.0.0-alpha.4 - 2025-01-03

Fixed

[TS] Make discriminated union .Is* properties works (@MangelMaxime)
[JS/TS/Python] Fix h in DateTime.ToString (@MangelMaxime)
[JS/TS] Fix hh in DateTime.ToString (@MangelMaxime)
[JS/TS] Don't generate the setter code if a property is decorated with [<Erase>] (@MangelMaxime)

5.0.0-alpha.3 - 2024-12-18

Fixed

[Python] Fix type testing against uint8, uint32, uint64, decimal (@MangelMaxime)
[JS/TS] Workaround source map generation bug (deteriorate them a little) (@MangelMaxime)

5.0.0-alpha.2 - 2024-11-25

Fixed

[All] Allow Fable 5 to be used with Fable 4 plugins (@ncave)

5.0.0-alpha.1 - 2024-11-24

Added

[All] Add --legacyCracker as a fallback (@MangelMaxime)

Changed

[All] Make MSBuildCracker the default (@MangelMaxime)
[All] Replace FABLE_COMPILER_4 with FABLE_COMPILER_5 as the compiler directive (@MangelMaxime)
[All] Move TargetFramework to net8.0 (@ncave)

4.24.0 - 2024-11-19

Added

[JS/TS] Added missing ResizeArray.CopyTo replacements (by @ncave)
[JS/TS] Added missing Dictionary constructors from enumerable (by @ncave)

Fixed

[Rust] Fixed import path rewrite (by @ncave)
[Rust] Updated derived interfaces (by @ncave)
[Rust] Updated string comparisons (by @ncave)
[Rust] Fixed derived traits mapping (by @ncave)
[JS/TS] Added missing ICollection helpers (#3914) (by @ncave)
[JS/TS] Added missing IReadOnlyCollection helpers (by @ncave)

4.23.0 - 2024-10-28

Added

[Rust] Added basic class inheritance support (by @ncave)
[Rust] Added String.Replace(char, char) and test (by @ncave)
[Rust] Support type extensions for external types (by @ncave)
[Rust] Support more System.Array methods and tests (by @ncave)
[Rust] Added decision tree multiple target references (by @ncave)
[Rust] Added Char surrogate tests for completeness (by @ncave)
[JS] Add System.String.Normalize support (by @DashieTM)
[JS] Allow [<Erase>] to work on members (by @MangelMaxime)

Fixed

[Rust] Updated derived traits mapping (by @ncave)
[Rust] Updated some collections equality (by @ncave)
[Rust] Fixed try finally handler order of execution (by @ncave)
[JS/TS/Python/Rust] Fixed String.StartsWith/EndsWith (#3934) (by @ncave)
[All/Rust] Removed Regex.Replace from hot paths (by @ncave)
[JS] Fix regression, generate let variable when using import on a private mutable variable (by @MangelMaxime)
[TS] Prevent generics to be duplicated (by @MangelMaxime)
[TS] Fix interface generation when decorated with Mangle (by @MangelMaxime)

4.22.0 - 2024-10-02

Added

[Rust] Added support for Dictionary/HashSet comparers (by @ncave)
[Rust] Updated support for interface object expressions (by @ncave)
[Rust] Added missing ResizeArray methods and tests (by @ncave)
[Rust] Added Async.Sleep and test (by @ncave)

Fixed

GH-3900 [Python] Fix nuget packages with hypens in their names (by @MangelMaxime)
[Rust] Uncurry field types for object expressions (by @ncave)
[Rust] Fixed pattern matching on this argument (by @ncave)
[All] Fixed Missing DU member with interface (#3915) (by @ncave)
[TS] Fixed missing Async type signature (#3864) (by @MangelMaxime)

4.21.0 - 2024-09-19

Added

[JS/TS] Add support for OrdinalIgnoreCase overload for String.EndsWith (#3892) (by @goswinr)
[JS/TS] Add uri.Port, uri.IsDefaultPort (by @MangelMaxime)

Changed

[Python] Remove $ sign when reporting an error from assert_equal and assert_not_equal (#3878) (by @joprice)
[All] Don't hide original error when failing to scan an assembly for plugin (#3896) (by @MangelMaxime)

Fixed

[JS/TS] Fix escaping of { and } in FormattableString (#3890) (by @roboz0r)
[JS/TS] Fix uri.Host to return the host name without the port (by @MangelMaxime)
[JS/TS] Fix TypeScript compilation by resolving type of jsOptions (#3894) (by @ManngelMaxime)

4.20.0 - 2024-09-04

Added

[Rust] Added support for static interface calls (by @ncave)

Fixed

[All] Fixed passing delegates with unit args (#3862) (by @ncave)
[JS/TS] Fixed Decimal comparisons (#3884) (by @ncave)
[Rust] Fixed return type for byref body (by @ncave)

4.19.3 - 2024-06-17

Fixed

[JS/TS] Fixed unwrapping optional arguments (#3847) (by @ncave)

4.19.2 - 2024-06-13

Fixed

[JS/TS] Fixed BigInt.ToDecimal with negative values (#3500) (by @ncave)

4.19.1 - 2024-06-13

Fixed

[All] Ignore testers for erased union cases (#3658) (by @ncave)
[All] Fixed Fable compiler hanging on some errors (#3842) (by @ncave)
[JS/TS] Fixed DateTime.MinValue, DateTime.MaxValue (#3836) (by @ncave)
[JS/TS] Fixed missing field using TypeScriptTaggedUnion (#3837) (by @ncave)

4.19.0 - 2024-06-10

Fixed

[TS] Fixed interface indexers (#3830) (by @ncave)
GH-3835 [All] Use case insensitive comparison when searching for dependencies between fable packages (by @ThisFunctionalTom)

4.18.0 - 2024-05-23

Fixed

GH-3817 [All] Fix broken --precompiledLib switch (#3818) (by @DunetsNM)
[JS/TS] Fixed TimeSpan.FromMilliseconds (#3815) (by @ncave)
[Python] Fixed quotation for union string cases (by @dbrattli)
[Python] Fixed casing issues with identifiers and reflection info (#3811) (by @dbrattli)
[JS/TS/Python] Fixed interface static members (#3566) (by @ncave)

4.17.0 - 2024-04-23

Added

[Rust] Added support for XmlDoc comments (by @ncave)
[Rust] Support captures in object expressions (by @ncave)
[Rust] Added type extensions support (by @ncave)
[Rust] Added Char implementation module (by @ncave)

Fixed

[Python] Fixes for custom hash values (#3796) (by @dbrattli)
[Python] Fix for import of camelCased class (#3808) (by @dbrattli)
[JS/TS] Fixed optional args for reflection (by @ncave)
[JS/TS] Fixed type visibility when parent is namespace (by @ncave)
[JS/TS] Fixed DateTimeOffset.ToString with custom format (by @ncave)
[Rust] Fixed property get on constrained generic types (by @ncave)
[Rust] Fixed module member imports (by @ncave)

4.16.0 - 2024-03-20

Added

[JS/TS] Add ConditionalWeakTable (by @chkn)

Fixed

GH-3778 [Python] Fixed custom hash values on Record types (by @dbrattli)

4.15.0 - 2024-03-18

Fixed

[JS/TS] Fixed DateTime.Add for DateTimeKind.Unspecified (by @ncave)
[Rust] Fixed deprecated NaiveDateTime usage in DateTime (by @ncave)
[Rust] Fixed generic interface implementation types (by @ncave)
[Rust] Fixed Dictionary constructor from IEnumerable (by @ncave)
[Rust] Fixed Seq.cast support for arrays and lists (by @ncave)
[JS/TS] Boolean.tryParse should not crash on null string (@goswinr)

Added

[Rust] Added some boxing support (by @ncave)

4.14.0 - 2024-03-01

Fixed

GH-3769 [All] Local plugin build does not run indefinably. (by @nojaf)
GH-3769 [JS/TS] Types hidden by signature files should not be exported. (by @nojaf)
GH-3772 [JS/TS] Re-implement DateTime.ToString custom format handling (by @MangelMaxime)

It now supports all custom format specifiers, and behave as if CultureInfo.InvariantCulture was used (Fable does not support Globalization).
GH-3772 [JS/TS] Make compilation fails if calling DateTime constructor with microseconds (by @MangelMaxime)

JavaScript Date does not support microseconds, we need to wait for Temporal to be widely supported before reconsidering this.
GH-3773 [Python] Fix DateTime custom format fffffff and FFFFFFF (by @MangelMaxime)

Changed

GH-3772 [JS/TS] Split replacement for DateTime and DateTimeOffset (by @MangelMaxime)

4.13.0 - 2024-02-13

Added

JavaScript

GH-3759 Add StringBuilder.Chars (by @MangelMaxime)
Added range overload for String.ToCharArray (by @ncave)

Rust

GH-3761 Added StringBuilder.Chars, StringBuilder.Remove and tests. (by @ncave)

Dart

GH-3761 Added StringBuilder support and tests. (by @ncave)

Fixed

JavaScript

GH-3748 Accessing an array out of bounds should emit an exception (by @MangelMaxime)
GH-3748 Setting an array out of bounds should emit an exception (by @MangelMaxime)
GH-3761 Fixed incorrect StringBuilder.Remove implementation. (by @ncave)

Python

GH-3761 Fixed incorrect StringBuilder.Remove implementation. (by @ncave)

Changed

JavaScript

GH-3761 Updated StringBuilder to remove allocations where possible. (by @ncave)

Python

GH-3761 Updated StringBuilder to remove allocations where possible. (by @ncave)

4.12.2 - 2024-02-13

Changed

Update to Fable.AST 4.4.0

4.12.1 - 2024-02-13

Fixed

JavaScript

Embed fable-library-js in Fable DLL (by @MangelMaxime)

4.12.0 - 2024-02-12 [YANKED]

Added

All

GH-3733 GH-3727 Add support for more Result API (by @zprobinson)
- Result.isOk
- Result.isError
- Result.Contains
- Result.Count
- Result.DefaultValue
- Result.DefaultWith
- Result.Exists
- Result.Fold
- Result.FoldBack
- Result.ForAll
- Result.Iterate
- Result.ToArray
- Result.ToList
- Result.ToOption
GH-3721 Add --test:MSBuildCracker flag allowing to use the experimental MSBuildCracker (by @nojaf)

JavaScript

GH-3745 Add support for ListCollector (by @nojaf)
- instance.Add
- instance.AddMany
- instance.AddManyAndClose
- instance.Close

Removed

JavaScript

Remove Choice.d.ts from source code of fable-library (by @MangelMaxime)
GH-3748 Accessing an array out of bounds should emit an exception (by @MangelMaxime)

TypeScript

Remove Choice.d.ts from source code of fable-library (by @MangelMaxime)
GH-3748 Accessing an array out of bounds should emit an exception (by @MangelMaxime)

Fixed

Python

GH-3717 Nested type with Custom Equality gives false negative equality (by @dbrattli)
Generate assert statements for assert expressions in debug mode (by @dbrattli)

All

GH-3744 Fix behaviour when passing --verbose to be consistent with behaviour before changing the logging library (by @nojaf)

Changed

JavaScript

GH-3749 Rename fable-library to fable-library-js (by @MangelMaxime)

4.11.0 - 2024-01-30

Changed

All

GH-3719 Restore dependencies against the .fsproj after evaluating the fable-temp.csproj file (Improves IDE supports) (by @MangelMaxime)
Don't delete fable_modules when re-evaluating the project file after a changes has been detected (Improves HMR experience) (by @MangelMaxime)

Fixed

All

GH-3723 Fix logger initialisation to allow --version to work (by @MangelMaxime)

JavaScript

GH-3716 System.Array.Resize: also handle the case where the array is null (by @chkn)

4.10.0 - 2024-01-25

Fixed

All

Fixed function composition types (by @ncave)
GH-3668 Normalize fable-library argument (by @nojaf)
GH-3682 Support some custom unary math operors (Acos, Asin, Atan, Atan2, Cos, Cosh, Exp, Log, Log2, Log10, Sin, Sinh, Sqrt, Tan, Tanh) (by @PierreYvesR)
GH-3603 Port back fixes for missing .gitignore file in the generated fable_modules/ folder (by @MangelMaxime)
GH-3684 Re-compile files from fable_modules after changing the project file in watch mode (by @OrfeasZ)

Javascript

Fixed 'System.Collections.Generic.Queue' bug (by @PierreYvesR)
Fixed instance calls for generic comparers (by @ncave)

Python

Fixed nested type with custom hashcode (by @dbrattli)
Add 'Double.IsPositiveInfinity' (by @PierreYvesR)
GH-3666 Fix for DateTime and TimeSpan addition (by @dbrattli)
GH-3663 Fix DateTime.Parse and DateTime.TryParse (by @MangelMaxime)

JavaScript

Fix DateTime.Parse when providing a 1 digit hour for PM times (3:5:34 PM) (by @MangelMaxime)

Rust

Fixed unary negation for signed integer MinValue (by @ncave)
Fixed excluding signature files from imports (by @ncave)
Fixed generic try_catch closure trait (by @ncave)
Fixed self arg capture in methods (by @ncave)
Fixed 'System.Collections.Generic.Queue' bug (by @PierreYvesR)
Added support for generic comparers (by @ncave)

Changed

All

GH-3671 Use Microsoft.Extensions.Logging (by @nojaf)
GH-3634 Suffix temporary csproj with .fable-temp.csproj and include a comment in the file (by @MangelMaxime)

Dart

Fix DateTime.DayOfWeek (by @MangelMaxime)

Added

Python

GH-3663 Complete rewrite of DateTime supports (by @MangelMaxime)

Special thanks to @dbrattli and @ncave for their help
- Constructors
  - From (year, month, day) up to (year, month, day, hour, minute, second, millisecond, microsecond) (with and without DateTimeKind)
  - From ticks (with and without DateTimeKind)
- Instance methods:
  - dt.Year
  - dt.Month
  - dt.Day
  - dt.Hour
  - dt.Minute
  - dt.Second
  - dt.Millisecond
  - dt.Microsecond
  - dt.ToUniversalTime
  - dt.DayOfWeek
  - dt.DayOfYear
  - dt.ToShortDateString
  - dt.ToShortTimeString
  - dt.ToLongDateString
  - dt.ToLongTimeString
  - dt.ToString
  - dt.ToLocalTime
  - dt.Date
  - dt.AddYears
  - dt.AddMonths
  - dt.AddDays
  - dt.AddHours
  - dt.AddMinutes
  - dt.AddSeconds
  - dt.AddMilliseconds
  - dt.AddMicroseconds
  - dt.Kind
- Static methods:
  - DateTime.Today
  - DateTime.Now
  - DateTime.Now
  - DateTime.UtcNow
  - DateTime.MinValue
  - DateTime.MaxValue
  - DateTime.Parse
  - DateTime.TryParse
  - DateTime.SpecifyKind

JavaScript

GH-3715 Add support for System.Array.Resize (by @chkn)

4.9.0 - 2023-12-14

Fixed

Python

GH-3655 Fix for Python output file names (by @dbrattli)
GH-3660 Fix for decimal to string with culture (by @dbrattli)

4.8.1 - 2023-12-12

Fixed

All

Fix the version reported by Fable (@MangelMaxime)

4.8.0 - 2023-12-12

Changed

All

Updated FCS to fce0cf00585c12174fa3e51e4fc34afe784b9b4e (by @ncave)
GH-3675 Breaking Change static members always require static member, disregarding FCS from F# v7.0 and early v8.0 supported dismissing the member keyword.

Added

Python

GH-3645 Add TimeSpan.Parse and TimeSpan.TryParse support to Python (by @MangelMaxime)
GH-3649 Add List.sortBy (by @dbrattli)
GH-3638 Add Array.sort and Array.sortDescending (by @dbrattli)

Fixed

JavaScript

GH-3465 Fix string.IndexOfAny (by @pkese)

Python

GH-3465 Fix string.IndexOfAny (by @pkese)

4.7.0 - 2023-12-06

Added

All

Overall performance improvements
- GH-3620 Removed double-dictionary lookups (by @Thorium)
- GH-3624 Add G-Research analyzers and fix reported issues (by @nojaf)

Fixed

All

GH-3603 Missing .gitignore file in the generated fable_modules/ folder (by @MangelMaxime)
GH-3712 Fix type of dereferenced byref (by @chkn)

Python

GH-3648 Records containing different values return the same hash code (by @dbrattli)

Python

GH-3617: Fix comparaison between list option when one is None (by @mangelmaxime)
GH-3615: Fix remove from dictionary with tuple as key (by @dbrattli)
GH-3598: Using obj () now generated an empty dict instead of None (by @dbrattli)
GH-3597: Do not translate .toString methods to str (by @dbrattli)
GH-3610: Cleanup Python regex handling (by @dbrattli)
GH-3628: System.DateTime.Substract not correctly transpiled (by @dbrattli)
GH-3640: All union cases return the same hash code (by @dbrattli)

4.6.0 - 2023-11-27

Changed

All

Updated .NET metadata to 8.0.100 (by @ncave)

Added

All

Fix #3584: Unit type compiles to undeclared variable (by @ncave)

Python

Support DateTime(..., DateTimeKind.Utc).ToString("O") (by @MangelMaxime)

Rust

Added Guid.TryParse, Guid.ToByteArray (by @ncave)

Fixed

Python

Fixed char to string type regression with binary operator (by @dbrattli)
Fix DateTime(..., DateTimeKind.Local).ToString("O") (by @MangelMaxime)
Fix calling value.ToString(CultureInfo.InvariantCulture) (by @MangelMaxime)
Fix #3605: Fix record equality comparison to works with optional fields (by @MangelMaxime and @dbrattli)
PR #3608: Rewrite time_span.py allowing for better precision by using a number representation intead of native timedelta. (by @MangelMaxime)

4.5.0 - 2023-11-07

Changed

Python

Use Any type for all non-repeated generic arguments (by @dbrattli)
Don't generate unnecessary type type-vars if generic type is replaced by Any (by @dbrattli)
Generate new style _T | None instead of Optional[_T] (by @dbrattli)

Rust

Support multiple namespaces sharing a prefix in the same file (by @ncave)
Support imports with the same namespace across multiple files (by @ncave)

Fixed

JavaScript

Fix #3571: [<AttachMembers>] not compatible with f# member this.Item (by @ncave)

4.4.1 - 2023-10-25

Changed

All

Fix #3567: Turn off FCS warning 3560 by default (by @vzarytovskii)

Fixed

Rust

Fixed recursive lambda captured idents cloning (by @ncave)

4.4.0 - 2023-10-24

Changed

All

Updated FCS to bd66d54b1ac4dd0f252c0a37196c2ccd54628356 (by @ncave)

JavaScript

Support (un)curry up to 20 arguments (by @MangelMaxime)

Python

Remove support for Python 3.9. Add GH testing for Python 3.12 (by @dbrattli)
Support (un)curry up to 20 arguments (by @MangelMaxime)

Dart

Support (un)curry up to 20 arguments (by @MangelMaxime)

4.3.0 - 2023-10-14

Fixed

JavaScript

Fix #3541: Interface imported in generated javascript when DU has an interface type constraint (by @ncave)

Python

Fixed Async.Parallel (by @dbrattli)

Changed

JavaScript

Improve error messages for Decimal.Parse, Double.Parse, Int32.Parse, Long.Parse (by @ncave)

Rust

Improve error messages for BigInt.Parse, DateOnly.Parse, DateTime.Parse, DateTimeOffset.Parse, Decimal.Parse, TimeOnly.Parse (by @ncave)

Python

Improve error messages for Double.Parse, Int32.Parse, Long.Parse (by @ncave)
Refactored async trampoline leveraging asyncio mainloop. (by @dbrattli)

Added

Python

Added Async.StartChild (by @dbrattli)
Fix #3482: Revert removal of Py.python and Py.expr_python (by @dbrattli)

4.2.2 - 2023-10-14

Fixed

Python

Fix #3527: Fix error name '...' is not defined (by @dbrattli)
Fix #3496: Python target is confused with class taking a length: int argument (by @dbrattli)

4.2.1 - 2023-09-29

Fix package to include Fable libraries folders

4.2.0 - 2023-09-29

Fix #3480: Function decorated with [<NamedParams>] without arguments provided should take an empty object
Fix #3494: Calling an attached parametrized getter fails in transpiled javascript
Remove fable-py support
Fix #3461: Don't default to javascript if the language requested by the user is unknown (help detect typo)
Improve --help message for the --lang section
Fix #3464: Invalidate cache when the target language changes
Always delete the fable_modules folder when the cache is invalidated
Remove --typescript options support, use --lang <target> instead
Fix #3441: Don't ignore error when loading plugin
Fix #3482: Remove Py.python and Py.expr_python use emitPyStatement and emitPyExpr instead
Restrict replacements to accept only functions from their target language module
Fix #3528: Consider functions hidden by a signature file as private (@nojaf)
Improve error message when Fable doesn't find the fable-library folder.

This is especially useful when working on Fable itself, and should save time to others. Each time I got this is error, I needed several minutes to remember the cause of it.

4.1.4 - 2023-05-16

Fix #3438: Source maps
Fix #3440: Don't curry arity-1 functions
Fix #3452: DateTimeOffset conversion to DateTime
Fix regression: Don't type test interfaces declared in F# code
Rust: Added no_std test build
Rust: Added regex support
Rust: Fixed no_std support
Rust: Fixed uncurried options
Rust: Enabled some applicative tests
Rust: Enabled some tests
Rust: Updated switch transform (#3449)
Rust: Updated dependencies (#3447)
Rust: Fixed interface properties (#3445)
Rust: Updated object equality (#3444)
Rust: Enabled some Comparison tests (#3442)
Rust: Added DateOnly, TimeOnly tests
Rust: Added DateTimeOffset tests
Rust: Updated TimeSpan
Rust: Added DateTimeOffset

4.1.3 - 2023-04-28

JS/TS/Rust: Added bigint log, log2, log10, minMag, maxMag
TS: Fix extension of files in fable_modules with out dir
TS: Support annotations of StringEnum and TypeScriptTaggedUnion types
JS/TS: Output JS docs
Fix range of inlined functions

4.1.2 - 2023-04-22

Print minimum fable-library version from npm

4.1.1 - 2023-04-22

Fix fable-library package.json

4.1.0 - 2023-04-18

Set TypeScript compilation as stable
Added Map.minKeyValue and maxKeyValue

4.1.0-beta-001 - 2023-04-16

Fix #3418: Single-Case Union Reflection
Include declaration .d.ts files in fable-library
Update FCS
Python: Implement missing bigint functions @johannesmols
TS: Fix #3415: ident type of uncurried lambdas
TS: Don't use const enums to represent union tags
TS: Fix function type annotation
TS: Get generic types of generated members
TS/JS: Sanitize class fields

4.0.6 - 2023-04-08

JS Hotfix: Skip compiler generated decls
TS: Fixes for unions, pattern matching and interface function getters

4.0.5 - 2023-04-08

Use native JS BigInt for int64/uint64
Fix #3402: Rust type mismatch error when compiling F# closure code
Improve optional field and argument typing in TypeScript
Fix fable-library-ts when used with Vite

4.0.4 - 2023-04-04

Fix #3397: Curry only user imports
Fix: Compiler Exception when !!, Anon Record, and aliased Ux (also behind option) @Booksbaum
Use native bigint type @ncave
Emit Fable erased unions as TS union types
Optimize compile time equality and testing (union, list, options)
TypeScript: enable Comparison, Convert and Event tests

4.0.3 - 2023-03-30

Fix #3389: Don't wrap TemplateStringArray
Rust: Fix recursive closures and some type tests,
TypeScript: Emit interfaces and anonymous record annotations

4.0.2 - 2023-03-27

Enable Unicode identifiers @kant2002
Add ability for plugins to remove member declaration @Zaid-Ajaj
Improve uncurrying mechanism and make it consistent across languages
Rust: Enable applicative tests and other fixes
TypeScript: Enable 1909 tests

4.0.1 - 2023-03-18

Fix #3371: Copying struct records
Php: Improve output @entropitor
Rust: string improvements
TypeScript: Fix applicative tests

4.0.0 - 2023-03-14

Fable JS stable release

4.0.0-theta-018 - 2022-11-19

When using a .csproj, make sure the project is restored before parsing
Rust, added Stack, Queue

4.0.0-theta-017 - 2022-11-16

Use TargetFramework from .fsproj and ask users to upgrade from netstandard2.0 if necessary
Update FCS (F# 7)
Python, handling static getters
Rust, fix deprecated API

4.0.0-theta-016 - 2022-11-13

Attempt to improve project parsing
Added Double.Pow static

4.0.0-theta-015 - 2022-11-05

JS, enable calls with importValueDynamic
JS, Support System.Delegate.DynamicInvoke
Rust, Added feature for func_type_enum
Rust, Added Func type wrappers (#3250)

4.0.0-theta-014 - 2022-10-31

Try to fix #3244 (cannot parse .fsproj)
Rust, added small string type
Python, fix byte array tying issue
JS, don't mangle idents from imports in emitted code
JS, optimize some array transforms

4.0.0-theta-012 - 2022-10-14

Python, option fixes
Python, fixes for reference equals with literals
Python, reduce the number of generated arrow functions
Rust, Added bigint support
Use Buildalyzer for parsing .fsproj

4.0.0-theta-011 - 2022-10-04

Python, add read/write files
Python, fix URI and number types
JS, allow imports in emit expressions and JSX
JS, improve import path resolution (interpolation, inlined functions)
TypeScript, fix arithmetic tests

4.0.0-theta-010 - 2022-09-28

Use StringTemplate expr in Fable AST for Python

4.0.0-theta-009 - 2022-09-28

Add language status to version
Make --runScript compatible with Python, Rust and Dart
Update F# compiler
Compile as net6 binary
TypeScript, type-safe union types and other fixes

4.0.0-theta-008 - 2022-09-22

Enable emitExpr/Statement with interpolation, @alfonsogarciacaro
Python, fix imported interfaces from other modules, @dbrattli
Python, allow python code embedder to return generic type T
Python, enable eliding async/await, @dbrattli
TypeScript, added library-ts to packages, @ncave
Python, do not trim emitted statements

4.0.0-theta-007 - 2022-09-21

TypeScript, fix fable-library-ts @ncave
Python, fix regex tests @dbrattli
Python, fix emit expressions
JS, helpers for JSX/React apps

4.0.0-theta-006 - 2022-09-18

Python, regex fixes for group collection

4.0.0-theta-005 - 2022-09-17

Python, fix type annotation for imports of erased interfaces
Python, better regex handling
TypeScript, ixed some array issues
Allow alias for default/namespace imports
TypeScript, added some interface annotations

4.0.0-theta-004 - 2022-09-14

JS, allow alias for default/namespace imports

4.0.0-theta-003 - 2022-09-12

Python, fix regression when building on Windows
Rust, added Default for array, string, hashmap, hashset, guid

4.0.0-theta-002 - 2022-09-11

Rust, removed cloning after emit
Python, make sure module names are valid
Python, fix interface entity lookup
Python, fixes for .ToArray and is_array_like
Rust, fixed TimeSpan fields

4.0.0-theta-001 - 2022-09-09

JSX, enable dynamic children
Python, fix dict remove
Rust, updated module visibility

4.0.0-snake-island-alpha-026 - 2022-09-08

Rust, more dates, @alexswan10k
Python, fix slice of string statements, @dbrattli
Python add task RunSynchronously, @dbrattli
Rust, ade startup an opt-in dependency, @ncave

4.0.0-snake-island-alpha-025 - 2022-09-06

Added IsInternal and IsPrivate properties in AST, @ncave
Rust, better datetime comparison + conversion. DateTimeOffset first, @alexswan10k
Python, GUID fixes, @dbrattli
Python, async/await fixes for Task returning functions, @dbrattli
Rust, another problematic ref counting scenario + fix, @alexswan10k

4.0.0-snake-island-alpha-024 - 2022-09-02

Fable.AST 4.0 stable
Rust, StringBuilder, Dates, ref counting

4.0.0-snake-island-alpha-023 - 2022-08-30

Update F# compiler
Make Fable 4 compatible with Feliz plugins
Rust, Fixed inner attributes (#3121)
Rust, Output crate attributes only on last file (#3119)
Rust, Added collection wrappers (#3118)
Rust, fix byref nested context not correctly propagating (#3103)
Rust, Fixed passing fields by ref (#3116)
Rust, Fixed struct record copy (#3114)
Rust, Output string type (#3113)
Python, type var cleanup. Use Any for types starting with $$ (#3100)
Rust, Fixed string format without args
Rust, Fixed closure ident cloning (#3106)
Rust, Fixed static, member and interface imports (#3105)

4.0.0-snake-island-alpha-021 - 2022-08-21

Rust, fixed curried apply, @ncave
Python, allow modules with uppercase letters, @dbrattli
Rust, added Math.DivRem support, @ncave
Rust, retain inlined funcs with CompiledName attr, @ncave
Python, fixes for extreme math values, @dbrattli
Rust, union fix for import prefixes, @alexswan10k
Rust, fixed build dependency for wasm32, @ncave

4.0.0-snake-island-alpha-020 - 2022-08-14

Rust, added Display trait, @ncave
Rust, Initial type testing support, @ncave
Python, typing fixes, @dbrattli
Python, Relax identifier checking to accept unicode chars, @dbrattli
Python, Generate Python data classes for records, @dbrattli
Rust, implement Thread ctor, start, and join. Implement lock fn. @alexswan10k
Rust, added decimals, @ncave
Python, better timespan handling, @dbrattli
Rust, added core assembly, @ncave
Rust, implement unsafe-cells feature switch + Monitor, @alexswan10k
Rust, initial support for object expressions, @ncave

4.0.0-snake-island-alpha-019 - 2022-07-31

Python, use --fableLib to choose between embedded or site-packages, @dbrattli
Rust - Make Map and Set support PartialEq, @alexswan10k
Rust, List/Map/Set cleanup, @ncave
Rust - more collection interop improvements, @alexswan10k

4.0.0-snake-island-alpha-018 - 2022-07-30

Python, array, list and resize-array fixes, @dbrattli
Rust, fable-library-rust cleanup, @ncave
Rust, Renamed List, Map, Set, @ncave
Rust, Merged ctor and static impl,@ncave
Rust, import deduping, @ncave
Rust, - More work on collection interop (Set, List, Map), @alexswan10k
Rust, - First pass at getting the interop experience with built in collections a little better, @alexswan10k

4.0.0-snake-island-alpha-017 - 2022-07-27

Python, reverted back to using modules instead of packages, @dbrattli
Rust, Fixed overload suffix for anon records, @ncave

4.0.0-snake-island-alpha-016 - 2022-07-26

Python, fixes for requirements.txt

4.0.0-snake-island-alpha-015 - 2022-07-26

Python, generate requirements.txt within fable_modules, @dbrattli
Rust, represent self as a Lrc[T] for method calls using double pointer indirection, @alexswan10k
Rust, fixed build issue, @ncave

4.0.0-snake-island-alpha-014 - 2022-07-25

Python, import fixes, @dbrattli
Rust, records and Unions now are correctly unwrapped when Struct attribute is used to tag as value, @alexswan10k
Rust, support struct anonymous records, @ncave
Rust, added support for struct tuples, @ncave
Rust, fixed struct constructors, @ncave
Rust, made Async optional, @ncave
Rust, added missing type import and slices, @ncave
Rust, comparison updates, @ncave
Make CancellationTokenSource implement IDisposable, @alfonsogarciacaro
Fixed Array.compareWith issue, @alfonsogarciacaro

4.0.0-snake-island-alpha-013 - 2022-07-25

Python, import fixes and package generation, @dbrattli
Python, use poetry for Python, @dbrattli

4.0.0-snake-island-alpha-012 - 2022-07-12

Update to latest FCS @ncave
Rust Support module imports @ncave
Rust: Implement basic thread pool + tasks + task builder @alexswan10k
Rust: Async builder, tasks, configurable pointer types @alexswan10k
Rust: attribute support @ncave

4.0.0-snake-island-alpha-011 - 2022-06-23

Fix import paths in Python

4.0.0-snake-island-alpha-010 - 2022-06-03

Use wrapping options for Dart

4.0.0-snake-island-alpha-008 - 2022-06-01

Rust and Dart fixes

4.0.0-snake-island-alpha-007 - 2022-05-25

JSX string templates

4.0.0-snake-island-alpha-006 - 2022-05-24

Dart: compile union cases as child classes

4.0.0-snake-island-alpha-005 - 2022-05-23

Dart fixes

4.0.0-snake-island-alpha-004 - 2022-05-21

Don't destructure props arg in JSX components

4.0.0-snake-island-alpha-003 - 2022-05-20

JSX Support

4.0.0-snake-island-alpha-002 - 2022-05-19

Snake Island alpha release 2

4.0.0-snake-island-alpha-001 - 2022-05-11

Snake Island alpha release

3.7.18 - 2022-08-16

Fix #3052: Nested options with Option.orElse #3052 @IanManske
Fix Fix #3078: Nested interpolation

3.7.17 - 2022-07-21

Fix #2961: Make Array.compareWith behaviour consistent with dotnet F#
Fix #2955: units of mesure with unsigned ints
Fix #2950: String formatting: trim trailing zeroes when using # placeholder
Fix #2879: Make CancellationTokenSource implement IDisposable
Don't print multiple sourceMappingURL comments

3.7.16 - 2022-07-05

Fix #2869: Don't update maps @hensou
Fix #2869: Use deterministic names for compiler-generate variables
Update FCS @ncave

3.7.15 - 2022-06-29

Fix #2869: Avoid unnecessary updates @hensou
Fix #2931: Array.IndexOf with non-primitive

3.7.14 - 2022-06-14

Fix #2924: Invalidate cache if source maps option changes
Fix #2925: Always set unicode flag for Regex
Enable non-booleans in Emit optional syntax

3.7.12 - 2022-05-27

Resolve defaultArg at compile time when possible
Fix #2900: Equality with prototype-less JS objects
Fix #2895: FableLibDir in cached info is empty when using --precompiledLib
Fix #2880: Trait call with unit of measure

3.7.11 - 2022-05-01

Fix generic param user/compiler generated name conflicts

3.7.10 - 2022-04-29

Fix #2864: Interface names don't conflict in JS
Fix #2855: duplicate idents from witness in inline expr
Fix #2868: don't write empty files
Add warning when duplicated generic params are detected

3.7.9 - 2022-04-01

Fix #2851: References captured by >> eagerly eval
Fix wrong out paths when using lower case drive letter

3.7.8 - 2022-03-24

Fix #2845: Cover more edge cases @Prunkles

3.7.7 - 2022-03-22

Fix #2840: Keep delegates of arity 1 curried @JaggerJo
Fix #2844: 1-len array slices starting at 0 work @jpacker
Fix #2845: Regex.Matches infinite loop @Prunkles

3.7.6 - 2022-03-16

Type.IsInstanceOfType works for interfaces decorated with Global/Import @chkn

3.7.5 - 2022-03-01

Prevent combining absolute paths

3.7.4 - 2022-02-25

Change intro message

3.7.3 - 2022-02-23

Fix #2832: Adding a converted char to string
Fix Type.IsSubclassOf(obj) @chkn

3.7.2 - 2022-02-22

Fix the fixes in the previous release

3.7.1 - 2022-02-17

Fix #2809: Generic trait calls in multiple nested inlined functions
Fix #2817: Optimization - Remove wrapping lambdas when possible

3.7.0 - 2022-02-07

Cache .fsproj parsing result
Run F# type check and Fable in parallel (use --noParallelTypeCheck flag to disable)
Automatic --runFast
Precompilation
--noReflection flag
Disable uncurrying functions passed as arguments to local lambdas
Seeded System.Random
Fix typeof(obj).IsInstanceOfType @chkn
Fix #2709: error when using JsInterop.import in inlined functions
Fix #2719: use with null disposable

3.7.0-beta-015 - 2022-01-26

Run sub-process even if compilation was skipped

3.7.0-beta-014 - 2022-01-24

Add --noParallelTypeCheck option to disable F#/Fable parallel compilation

3.7.0-beta-012 - 2022-01-18

Disable uncurrying functions passed as arguments to local lambdas
Fix typeof(obj).IsInstanceOfType @chkn

3.7.0-beta-011 - 2022-01-14

Fixes for precompiling inline expressions
Fix #2719: use with null disposable
Fix #2727: don't write in same line when output redirected

3.7.0-beta-009 - 2022-01-12

Fix #2718
Other stability issues and add more verbose logs

3.7.0-beta-008 - 2022-01-11

Prevent Fable from getting stuck on fatal errors
Show File compiled messages in CI

3.7.0-beta-007 - 2022-01-11

Lock file for outDir (mainly intended for parallel processes precompiling the same library)

3.7.0-beta-006 - 2022-01-11

Allow inlined functions accessing internal values in Fable.Precompiled.dll (FCS)
Shorten logs in same line if longer than 80 chars (so they don't jump to next line)
Check paket.references/paket.lock when checking if project cracker cached info is outdates
Add flag to disable reflection
Fix #2709: error when using JsInterop.import in inlined functions

3.7.0-beta-005 - 2022-01-07

Fix cache issues
Seeded random

3.7.0-beta-004 - 2022-01-05

Fix watch mode and runFast optimization

3.7.0-beta-003 - 2022-01-04

Fix precompile errors

3.7.0-beta-002 - 2021-12-28

Performance improvements

3.7.0-beta-001 - 2021-12-20

Add precompile command

3.6.3 - 2021-12-01

New FSharp.Core 6 APIs: updateAt/insertAt/insertManyAt/removeAt/removeManyAt
Support thousand separators in String.Format
Fix #2628 @stroborobo

3.6.2 - 2021-11-26

TypescriptTaggedUnion @cannorin
Speed up recompilation when adding/removing files

3.6.1 - 2021-11-23

Fix #2614: Char addition
Fix #2615: Math.DivRem
Fix string template literals
Improve Regex.Match/IsMatch/Matches
Update FCS

3.6.0 - 2021-11-19

Support F# 6
Support DateOnly/TimeOnly @kerams
Improve watch mode
Cache project options

3.6.0-beta-003 - 2021-11-17

Add Fable.Core.Compiler.triggeredByDependency flag
Support DefaultParameterValue attribute (not for JS interop)
Update F# compiler

3.6.0-beta-002 - 2021-11-15

Fix watch mode when saving multiple files at same time
TimeOnly.FromDateTime @kerams
Remove --watchDeps flag

3.6.0-beta-001 - 2021-11-14

Support F# 6
Support DateOnly/TimeOnly @kerams
Improve watch mode
Add --watchDeps flag
Cache project options

3.4.10 - 2021-11-08

Add support for StringSplitOptions.TrimEntries @steveofficer
Fix #2587: DateTimeOffset.Parse issues with some locales @ncave
Use Process.ArgumentList to escape args passed to subprocess
Print paths relative to --cwd if set

3.4.9 - 2021-11-05

Add CLI arg --watchDelay
Show relative paths in logs
Fixed Seq.toArray @ncave
Fix FullName/Name/Namespace of complex array types

3.4.8 - 2021-11-04

Fix #2572 #2579: Watch .fsi files and referenced .fsproj
Fix #2576: Last file can omit module declaration
Fix Seq.cache with partial enumeration
Fix DateTime Offset parsing with date only and hyphens
Set NODE_ENV when running a sub-process

3.4.7 - 2021-10-28

Fix #2571: Forward slash not escaped when creating regex

3.4.6 - 2021-10-26

Small improvements in Async.ts

3.4.5 - 2021-10-21

Accept ${entryDir} macro in imports

3.4.4 - 2021-10-20

Use relative paths for source maps

3.4.3 - 2021-10-14

Add support of System.Activator for primitive types @Happypig375
Fix #2566: HashSet.IntersectWith does not respect custom comparer
Fix calling super from an override when the method was declared in grandparent
Compile to RegexConstant when possible
Pass Fable compiled name to ReflectedDecorator
Remove void wrapper in expression statements

3.4.2 - 2021-10-05

Fix #2561: Case insensitive args and check
Fix generic parameters with JS.ReflectedDecorator

3.4.1 - 2021-10-04

Support System.Collections.Generic.Queue @davedawkins
Fix custom array equality
Remove class restriction for ParamObject
Skip parens in emit if placeholder is already surrounded by parens

3.4.0 - 2021-10-01

ParamObject attribute
Rename .fable folder to fable_modules
Print log about Femto
Add Type.IsInstanceOfType @chkn
Fix #2229: Parsing succeeded for some invalid dates @njlr

3.3.1 - 2021-09-27

Fix #2097: Async.StartChild does not apply timeout @njlr
Fix #2530: System.Collections.Generic.Stack @njlr
Fix #2548: Assigning to value of unit type
Fix #2549: Native ESM support
Serialize compiler_info as JSON

3.3.0 - 2021-09-16

JS.Decorator/ReflectedDecorator attributes
Fix isSubclassOf to walk up the inheritance chain @chkn
Fix #2520: Uri.OriginalString @njlr
Fix #2532: Measure products
Optimize interpolate strings without formatting into JS templates

3.2.14 - 2021-09-11

Fix #2480: Include package.json in fable-library
Fix #2522: Warn if user sets .fable as outDir
Fix #2525: Support infinite arity for currying/uncurrying
Fix plugin version check

3.2.12 - 2021-08-26

Fix #2505: Make String.Split match .NET with no or null separators
Add TimeSpan.Divide and Multiply @0x53A
Add Async.Sequential @0x53A
Compile FormattableString as JS Templates

3.2.11 - 2021-08-19

Add --rootModule CLI flag

3.2.10 - 2021-08-02

Support System.Uri.TryCreate @Choc13
Fix #2477: Don't drop "DEBUG" and "TRACE" DefineConstants @stroborobo
Fix #2480: Improve tree shaking with fable-libray
Fix #2485: Proper representation of Choice with 3 or more items
Fix #2491: Unchecked.defaultof with struct tuples
Fix #2496: Custom Pow operator

3.2.9 - 2021-07-08

Don't print JS files in watch mode if there're F# errors
Fix SRTP with local inline functions

3.2.8 - 2021-06-26

Fix regression in FCS: passing SOURCE_IDENTIFIER to static parameters in type providers

3.2.7 - 2021-06-25

Fix regression: all files were recompiled in watch mode in 3.2.5
Fix #2472: Tuple-related methods

3.2.6 - 2021-06-22

Fix #2471: Trait call regression

3.2.5 - 2021-06-21

Fix #2468: SRTP Parser
Only show Compile file log in watch compilations

3.2.4 - 2021-06-16

Fix #2438: Print JS sequence expressions always between parentheses
Don't jump over mutable idents when inlining

3.2.3 - 2021-06-11

Experimental.namesofLambda

3.2.2 - 2021-06-03

Check for correct types in Anonymous Record when assigning to Interface with [<EmitIndexer>] via !! @Booksbaum
Fix #1973: FormattableString support

3.2.1 - 2021-05-28

Fix Event issues and and implement FSharpEvent`2 @chkn
Fix #2451: throw exception when sequence is empty @MNie
Fix #2445: Improve error message when fable doesn't implement an API

3.2.0 - 2021-05-28

Update to net5.0 and FCS, @ncave

3.1.16 - 2021-05-14

Publish with icon and symbols @cartermp

3.1.15 - 2021-04-16

Add a --sourceMapsRoot CLI option to set source maps sourceRoot @mlaily
Fix #2433: Improve type info for plugins like Fable.SvelteStore
Fix #2431: Pass output directory info to plugins

3.1.14 - 2021-04-09

Experimental casenameWithFieldIndex

3.1.12 - 2021-03-23

Fix #1678: BigInt native JS JSON serialization with toJSON
Fix #2151: Implement DateTimeOffset.toOffset @Booksbaum
Fix #2410: Invalid offsets are accepted @Booksbaum
Fix #2411: DateTime(Unspecified) fails when offset not local timezone @Booksbaum
Fix #2417: overloads with struct tuple
Fix #2418: List native JS JSON serialization with toJSON
Update big.js (decimals) @ncave
Update source-map-sharp to 1.0.5

3.1.11 - 2021-03-17

Fix watch compilation issues
Fix #2398: two successive string format placeholders and value of first one ends in %

3.1.10 - 2021-03-16

Revert breaking change, configuration should default to Debug only in watch mode @forki

3.1.9 - 2021-03-15

Fix crash with delegate alias

3.1.8 - 2021-03-15

Fix #2234: Recompile dependencies in watch mode when Emit/Import attributes change
Fix #2406: Check --outDir argument when running clean command

3.1.7 - 2021-03-11

Fix for Fable.Core.JsInterop.importValueDynamic

3.1.6 - 2021-03-11

Support setting a Build configuration with --configuration cli arg @stroborobo
Log compiled files in same line
Fix #2390: Array.choose is executing choose function two times @ncave
Fix #2394: interpolate doesn't unescape %% correctly @thinkbeforecoding
Fix #2396: custom exceptions in async workflows
Fix #2400: Conversion to delegates
Fix: Accessing named capture group in Regex only works with string constant @Booksbaum
Fable library improvements and other fixes @ncave

3.1.5 - 2021-02-18

Fix #2384: Polling file watcher @mlaily
Fix static constructors with attached members

3.1.4 - 2021-02-12

Fix #2045: Aliasing a function wrapping a multi-arity function in point-free style

3.1.3 - 2021-02-12

Add support for named capture groups in Regexes @Booksbaum
Babel AST: cleanup and refactor @dbrattli
Fix #1343: Warning when interface name clashes with record field @BillHally
Fix #2376: Char.IsLetter with “ and ” @ncave @NickDarvey
Fix #2372: Array.reduce Array.append @inosik
Fix #2367: Using "unbox null" for callback returns "undefined"
Fix #2357: Fall-through to default switch case duplicates the switch case consequent code block
Fix #2356: Curried functions mangled via DU, List.fold and match combination
Fix #2355: System.Math.Ceiling/Floor returning incorrect values for some Decimals @ncave
Fix #2350: Empty files
Fix #2116: Incorrect uncurrying with list of function options
Fix #2047: Iterating over a list of functions with a for in loop
Fix #2046: Assigning a function to scoped mutable variable
Fix #2045: Raise warning for point-free function declarations

3.1.2 - 2021-01-25

Fast copy for typed arrays @GordonBGood
Return error exit code when wront arguments passed
Fix source map writing
Fix #2350: Invalid JS class for empty files
Fix #2355: System.Math.Ceiling() and System.Math.Floor returning incorrect values for some Decimals @ncave
Fix #2357: Remove duplicate switch branches