Ready to dig deeper into F# 4.1?
Jonathan Allen provides an in-depth look at these new F# features.
The Visual Studio 2017 release in early March included F# 4.1 and an update of the Visual F# tools. F# 4.1 brings improvements and interoperation with C# 7 while the tools are the first version supporting the Roslyn workspaces.
As previously covered, F# 4.1 brings improvements and interoperation with C# 7:
- Struct tuples and support for C# value tuples
- Struct annotations for records and discriminated unions
fixedkeyword support- Underscores in numeric literals
- Caller info argument attributes
- Result type
- Mutually referential types and modules within the same file
- Byref returns and support for C# 7 ref-returning methods
- Error message improvements
- Implement IReadonlyCollection<’T> in list<’T>
- Additional option module functions
- Statically resolved type parameter improvements
- Compiler performance improvements
An updated version of the Visual F# tools also shipped with Visual Studio 2017. A notable addition to the tools is the support of Roslyn Workspace APIs:
A workspace is an active representation of your solution as a collection of projects, each with a collection of documents. A workspace is typically tied to a host environment that is constantly changing as a user types or manipulates properties.
IDEs such as Visual Studio use the Roslyn workspace APIs to provide multiple features. While the compiler part of Roslyn is C#/VB specific, some APIs such as the workspaces sit at a higher level and are not tied to a particular language. Thus, implementing the API means an IDE feature can support F# directly instead of needing a distinct implementation for F#. The features refactored to use Roslyn workspaces include:
- Find all references
- Navigation bar support
- Syntax and type colorization in hovers and signature help
- IntelliSense filters and glyph improvements
- Fuzzy matching on names in IntelliSense
- Better colorization in the editor
- Code Indentation improvements
- Breakpoint resolution improvements
- Go to definition improvements
- Ability to trigger Lightbulbs for various code fixes
- Semantic highlighting of tokens
- Support of Go to All feature (ctrl+T)
- Roslyn-style inline rename
The official announcement from Microsoft also acknowledges the many contributions of the F# community. Several community members were thanked for their contributions to the F# compiler, Visual F# tools and language design.