F#10 Brings Performance Improvements

"The release of .NET 10 brings with it F# version 10. It's a refinement‑focused update that enhances the language's ergonomics, improves performance, and optimises compiler behaviour for everyday functional development. For F# developers used to the patterns of F# 6‑9, many language improvements have focused on new syntax or major paradigms. With F# 10, the emphasis shifts: rather than introducing sweeping new features, the team targets clarity, consistency, and the performance foundations of large codebases."

"F# 10 allows marking optional parameters with [<Struct>] attribute. Under the hood, the compiler uses stack-allocated ValueOption<T> instead of a heap-allocated Option<T>, reducing memory allocations in code hot paths. Other .NET languages had this optimisation for some time, and now F# has gained parity with them. As for library and tooling improvements, async code that uses task expressions now can use and! keyword to await tasks more succinctly."

"As for language improvements, F# 10 introduces the #warnon directive paired with #nowarn, letting developers restrict suppression of compiler warnings to discrete code regions rather than disabling them globally. Developers can now define automatic public properties that are privately mutable, with member val X = ... with public get, private set, avoiding the verbose backing‐field pattern previously needed. // F# 9 type Ledger() = [<DefaultValue>] val mutable private _Balance: decimal member this.Balance with public get() = this._Balance and private set v = this._Balance <- v"

F# 10 focuses on refinement rather than major new paradigms, improving day-to-day ergonomics, performance and compiler behaviour for large codebases. The release adds #warnon to limit warning suppression to specific regions and enables automatic public properties with private setters to avoid verbose backing fields. Optional parameters can be marked with [<Struct>] so the compiler uses stack-allocated ValueOption<T> to reduce allocations in hot paths, bringing parity with other .NET languages. Tooling updates include the and! keyword in task expressions for succinct awaits. Additional performance work improves trimming and linked-file metadata handling.

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