Fable 5.0.0-alpha.23 released!

NewsBot · 3 February 2026 16:19

Fable 5.0.0-alpha.23 has been released.

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)

Link: Release 5.0.0-alpha.23 · fable-compiler/Fable · GitHub