Jan Jones
@janjones.me
C# (Roslyn) compiler dev at Microsoft
https://github.com/jjonescz
https://github.com/jjonescz
Fully revamped the tree view 🌳 in .NET Lab. Now with cursor syncing. Can display syntax, IOperation, and symbol info. #dotnet #csharp #roslyn #dotnetlab
October 5, 2025 at 3:58 PM
Fully revamped the tree view 🌳 in .NET Lab. Now with cursor syncing. Can display syntax, IOperation, and symbol info. #dotnet #csharp #roslyn #dotnetlab
Reposted by Jan Jones
Big improvements to the performance of developing C# file-based incoming. Subsequent builds/runs will cache MSBuild outputs & directly invoke the C# compiler if inputs don't change. This in addition to the work in rc.1 to avoid MSBuild completely for simple file-based apps
github.com/dotnet/sdk/p...
github.com/dotnet/sdk/p...
Reuse CSC arguments in file-based app runs by jjonescz · Pull Request #50635 · dotnet/sdk
Part of #48011.
This optimization saves CSC arguments when MSBuild runs and then reuses them in subsequent runs so dotnet run file.cs can skip MSBuild and invoke only the compiler.
In my simple exp...
github.com
September 11, 2025 at 5:58 PM
Big improvements to the performance of developing C# file-based incoming. Subsequent builds/runs will cache MSBuild outputs & directly invoke the C# compiler if inputs don't change. This in addition to the work in rc.1 to avoid MSBuild completely for simple file-based apps
github.com/dotnet/sdk/p...
github.com/dotnet/sdk/p...
Added a small but useful feature to copy the current URL in .NET Lab (lab.razor.fyi). It has a keyboard shortcut too: Ctrl+; 📋
#dotnet #csharp #roslyn #dotnetlab
#dotnet #csharp #roslyn #dotnetlab
September 6, 2025 at 1:04 PM
Added a small but useful feature to copy the current URL in .NET Lab (lab.razor.fyi). It has a keyboard shortcut too: Ctrl+; 📋
#dotnet #csharp #roslyn #dotnetlab
#dotnet #csharp #roslyn #dotnetlab
.NET Lab (lab.razor.fyi) just gained new configuration options inspired by `dotnet run app.cs`. Reference any NuGet packages via `#:package` or quickly change config via `#:property` (with editor suggestions to guide you). 🚀⚙️
July 26, 2025 at 3:54 PM
.NET Lab (lab.razor.fyi) just gained new configuration options inspired by `dotnet run app.cs`. Reference any NuGet packages via `#:package` or quickly change config via `#:property` (with editor suggestions to guide you). 🚀⚙️
Reposted by Jan Jones
Check out all the improvements to file-based apps (dotnet run app.cs) in preview.6 that went out today!
github.com/dotnet/core/...
github.com/dotnet/core/...
github.com
July 15, 2025 at 5:53 PM
Check out all the improvements to file-based apps (dotnet run app.cs) in preview.6 that went out today!
github.com/dotnet/core/...
github.com/dotnet/core/...
Reposted by Jan Jones
Blogged: Behind the scenes of dotnet run app.cs - Exploring the .NET 10 preview - Part 2
andrewlock.net/exploring-do...
In this post I looks at how the new single-file .NET run experience is implemented inside the .NET SDK, focusing on how the virtual-project file is built.
#dotnet #csharp
andrewlock.net/exploring-do...
In this post I looks at how the new single-file .NET run experience is implemented inside the .NET SDK, focusing on how the virtual-project file is built.
#dotnet #csharp
Behind the scenes of dotnet run app.cs: Exploring the .NET 10 preview - Part 2
In this post I looks at how the new single-file .NET run experience is implemented inside the .NET SDK, focusing on how the virtual-project file is built
andrewlock.net
July 8, 2025 at 5:47 PM
Blogged: Behind the scenes of dotnet run app.cs - Exploring the .NET 10 preview - Part 2
andrewlock.net/exploring-do...
In this post I looks at how the new single-file .NET run experience is implemented inside the .NET SDK, focusing on how the virtual-project file is built.
#dotnet #csharp
andrewlock.net/exploring-do...
In this post I looks at how the new single-file .NET run experience is implemented inside the .NET SDK, focusing on how the virtual-project file is built.
#dotnet #csharp
.NET Lab (lab.razor.fyi) now has Code Actions 🚀 Very useful when you paste some code snippet and want to add missing usings. But it can do much more - all Roslyn code fixes are included.
June 28, 2025 at 10:22 AM
.NET Lab (lab.razor.fyi) now has Code Actions 🚀 Very useful when you paste some code snippet and want to add missing usings. But it can do much more - all Roslyn code fixes are included.
Added semantic highlighting to .NET Lab (lab.razor.fyi)
June 22, 2025 at 1:04 PM
Added semantic highlighting to .NET Lab (lab.razor.fyi)
Reposted by Jan Jones
Completions and live diagnostics are now much improved and enabled by default in .NET Lab (lab.razor.fyi). Stay tuned for more enhancements to the editing experience coming soon.
May 16, 2025 at 7:05 AM
Completions and live diagnostics are now much improved and enabled by default in .NET Lab (lab.razor.fyi). Stay tuned for more enhancements to the editing experience coming soon.
Shared lab.razor.fyi snippets are now cached, so you can see the output even before the compiler is initialized. (Nevertheless, more optimizations of loading times are coming.) Example: lab.razor.fyi#47Lm4gooyk8v...
March 2, 2025 at 9:47 AM
Shared lab.razor.fyi snippets are now cached, so you can see the output even before the compiler is initialized. (Nevertheless, more optimizations of loading times are coming.) Example: lab.razor.fyi#47Lm4gooyk8v...
Added this cool loading animation to lab.razor.fyi. Suddenly the loading feels faster ⚡
February 21, 2025 at 5:34 PM
Added this cool loading animation to lab.razor.fyi. Suddenly the loading feels faster ⚡
Updated lab.razor.fyi to use Microsoft Fluent UI. Quite happy with the result. Also got dark mode for free.
December 20, 2024 at 5:33 PM
Updated lab.razor.fyi to use Microsoft Fluent UI. Quite happy with the result. Also got dark mode for free.