Microsoft maps out F# language upgrade

Microsoft’s plans for the F# “functional first” language include an upgrade later this year that adds capabilities ranging from struct tuples to improved error messages. Backing for .Net Core, a multiplatform, open source version of the .Net programming model, also is in the works.

F# 4.1 focuses on flexibility and incremental improvements, the Microsoft Visual FSharp team said. It features struct tuples and interoperability with Visual C# 7 and Visual Basic tuples.

Tuples are a data structure that can store a finite sequence of data of fixed sizes and can return multiple values from a method. Struct tuples improve performance when there are many tuples allocated in a short period of time.

“The tuple type in F# is a key way to bundle values together in a number of ways at the language level,” the team said. “The benefits this brings, such as grouping values together as an ad-hoc convenience, or bundling information with the result of an operation, are also surfacing in the form of struct tuples in C# and Visual Basic.”

Version 4.1 will also feature a struct records capability. “In F# 4.1, a record type can be represented as a struct with the [<Struct>] attribute. This allows records to now share the same performance characteristics as structs, without any other required changes to the type definition.”

Single-case struct unions, meanwhile, also are enabled. “Single-case union types are often used to wrap a primitive type for domain modeling,” the team said. “This allows you to continue to do so, but without the overhead of allocating a new type on the heap.”

Error messages will be enhanced in F# 4.1, featuring improvements in suggested fixes with information already contained in the compiler, and a fixed keyword capability is planned as well. The .Net Intermediate Language enables a developer to pin a pointer-type local on the stack; C# supports this with the “fixed” statement preventing garbage collection within the scope of that statement. “This support is coming to F# 4.1 in the form of the ‘fixed’ keyword used in conjunction with a ‘use’ binding,” said the team. Underscores in numeric literals version 4.1, meanwhile, will enable grouping of digits into logical units for easier reading.

F# 4.1 will enable a collection of types and modules within a single scope in a single file to be mutually referential, and it will include an implicit “module” suffix on modules sharing the same name as a type. “With this feature, if a module shares the same name as a type within the same declaration group — that is, they are within the same namespace, or in the same group of declarations making up a module — it will have the suffix ‘Module’ appended to it at compile-time.”

Visual F# Tools for F# 4.1 will support editing and compiling .Net Core and .Net Framework projects. “Our compiler and scripting tools for F# 4.1 will be the first version to offer support for .Net Core,” the team said. Planned tooling includes a cross-platform, open source compiler tool chain for .Net Framework and .Net Core for use with Linux, MacOS X, and Windows.

Visual F# IDE tools will be upgraded for use with the next version of Visual Studio, and F# 4.1 support will be included in Microsoft’s Xamarin Studio and Visual Studio Code tools. The upgrade will be supported in the Fable F#-to-ECMAScript transpiler and in Roslyn Workspaces, for code analysis and refactoring in the Roslyn compiler platform.