Visual Studio Code Extension

Flix comes with a fully-featured Visual Studio Code Extension:

Visual Studio Code1

The Flix extension uses the real Flix compiler hence all information (e.g. error messages) are always 1:1 with the real Flix programming language.

Flix also comes with an (optional) Visual Studio Code color theme called "Flixify Dark".


  • Semantic Syntax Highlighting

  • Diagnostics

    • Compiler error messages.
  • Auto-complete

    • Auto-complete as you type.
    • Auto-completion is context aware.
    • Type-directed completion of program holes.
  • Snippets

    • Auto-complete common code constructs.
  • Inlay Hints

    • Shows inline type information.
  • Type and Effect Hovers

    • Hover over any expression to see its type and effect.
    • Hover over any local variable or formal parameter to see its type.
    • Hover over any function to see its type signature and documentation.
  • Jump to Definition

    • Jump to the definition of any function.
    • Jump to the definition of any local variable or formal parameter.
    • Jump to the definition of any enum case.
  • Find References

    • Find all references to a function.
    • Find all references to a local variable or formal parameter.
    • Find all references to an enum case.
    • Find all implementations of a trait.
  • Symbols

    • List all document symbols.
    • List all workspace symbols.
  • Rename

    • Rename local variables or formal parameters.
    • Rename functions.
  • Code Lenses

    • Run main from within the editor.
    • Run tests from within the editor.
  • Highlight

    • Highlights semantically related symbols.
  • Semantic Tokens

    • Additional code highlighting hints provided by the compiler.

Known Limitations

  • There is a known issue with PowerShell and using file names that contain special characters. We recommend that Flix source files are given only ASCII names.

  • The extension assumes that you are working in "Workspace Mode", i.e. you must have a folder open which contains your Flix source code.

  • Upon startup, the Flix compiler has to load the entire Flix standard library into its caches which takes a few seconds.