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dotnet
roslyn
C#2015–2026
dotnet / roslyn

roslyn

The Roslyn .NET compiler provides C# and Visual Basic languages with rich code analysis APIs.

Languages & Compilers
Explore on GitHubRead Hacker News discussions
115Distinct people
143Mentions
1Explicit recommenders
20.8KGitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

The Roslyn .NET compiler provides C# and Visual Basic languages with rich code analysis APIs.

GitHub

Where it is used

No documented product use was verified in the last source check.

What people are saying

> - I love that they are adding REPL. I really wish C# had this Here you go :) https://github.com/dotnet/roslyn/wiki/C%23-Interactive-Walkt... Also: csi.exe. Try it :)

josteink used a recommendation phrase. One indexed comment matches. This is a phrase match, not a verdict.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

Mentioned in the same Hacker News threads. That is not proof they are substitutes.

This week on Hacker News

Nov 8–Nov 15 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/15/2026, 5:03:38 AM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year143 dated mentions

Observed mentions: 2015-01-14 23:49:47 UTC to 2026-05-11 08:56:48 UTC.

01020302015-01-01 00:00:00 UTC to 2016-01-01 00:00:00 UTC (exclusive): 32 mentions; 6 submissions, 26 comments20152016-01-01 00:00:00 UTC to 2017-01-01 00:00:00 UTC (exclusive): 28 mentions; 6 submissions, 22 comments2017-01-01 00:00:00 UTC to 2018-01-01 00:00:00 UTC (exclusive): 26 mentions; 2 submissions, 24 comments2018-01-01 00:00:00 UTC to 2019-01-01 00:00:00 UTC (exclusive): 6 mentions; 1 submissions, 5 comments2019-01-01 00:00:00 UTC to 2020-01-01 00:00:00 UTC (exclusive): 6 mentions; 0 submissions, 6 comments2020-01-01 00:00:00 UTC to 2021-01-01 00:00:00 UTC (exclusive): 12 mentions; 0 submissions, 12 comments20202021-01-01 00:00:00 UTC to 2022-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments2022-01-01 00:00:00 UTC to 2023-01-01 00:00:00 UTC (exclusive): 4 mentions; 0 submissions, 4 comments2023-01-01 00:00:00 UTC to 2024-01-01 00:00:00 UTC (exclusive): 3 mentions; 1 submissions, 2 comments2024-01-01 00:00:00 UTC to 2025-01-01 00:00:00 UTC (exclusive): 11 mentions; 1 submissions, 10 comments2025-01-01 00:00:00 UTC to 2026-01-01 00:00:00 UTC (exclusive): 8 mentions; 0 submissions, 8 comments2026-01-01 00:00:00 UTC to 2027-01-01 00:00:00 UTC (exclusive): 6 mentions; 1 submissions, 5 comments. Incomplete calendar period.2026*

* An incomplete calendar period is marked with an outlined bar. Its count is not directly comparable with a full period.

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
20152015-01-01 00:00:00 UTC2016-01-01 00:00:00 UTC32626
20162016-01-01 00:00:00 UTC2017-01-01 00:00:00 UTC28622
20172017-01-01 00:00:00 UTC2018-01-01 00:00:00 UTC26224
20182018-01-01 00:00:00 UTC2019-01-01 00:00:00 UTC615
20192019-01-01 00:00:00 UTC2020-01-01 00:00:00 UTC606
20202020-01-01 00:00:00 UTC2021-01-01 00:00:00 UTC12012
20212021-01-01 00:00:00 UTC2022-01-01 00:00:00 UTC101
20222022-01-01 00:00:00 UTC2023-01-01 00:00:00 UTC404
20232023-01-01 00:00:00 UTC2024-01-01 00:00:00 UTC312
20242024-01-01 00:00:00 UTC2025-01-01 00:00:00 UTC11110
20252025-01-01 00:00:00 UTC2026-01-01 00:00:00 UTC808
2026 (partial)2026-01-01 00:00:00 UTC2027-01-01 00:00:00 UTC615

From the project README

An excerpt from the repository, fetched Nov 13, 2026.

Read the project’s introduction
The .NET Compiler Platform Roslyn is the open-source implementation of both the C# and Visual Basic compilers with an API surface for building code analysis tools. C# and Visual Basic Language Feature Suggestions If you want to suggest a new feature for the C# or Visual Basic languages go here: dotnet/csharplang for C# specific issues dotnet/vblang for VB-specific features dotnet/csharplang for features that affect both languages Contributing All work on the C# and Visual Basic compiler happens directly on GitHub. Both core team members and external contributors send pull requests which go through the same review process. If you are interested in fixing issues and contributing directly to the code base, a great way to get started is to ask some questions on GitHub Discussions! Then check out our contributing guide which covers the following: Coding guidelines The development workflow, including debugging and running tests Submitting pull requests Finding a bug to fix in the IDE or Compiler Finding a feature to implement in the IDE or Compiler Roslyn API suggestions should go through the API review process Community The Roslyn community can be found on GitHub Discussions, where you can ask questions, voice ideas, and share your projects. To chat with other community members, you can join the Roslyn channel on the CSharp Community Discord. Our Code of Conduct applies to all Roslyn community channels and has adopted the .NET Foundation Code of Conduct. Documentation Visit Roslyn Architecture Overview to get started with Roslyn’s API’s. NuGet Feeds The latest pre-release builds are available from the following public NuGet feeds: Compiler: https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-tools/nuget/v3/index.json IDE Services: https://pkgs.dev.azure.com/azure-public/vside/_packaging/vssdk/nuget/v3/index.json .NET SDK: https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5/nuget/v3/index.json Continuous Integration status Builds Branch Windows Debug Windows Release Unix Debug main Desktop Unit Tests Branch Debug x86 Debug x64 Release x86 Release x64 main CoreClr Unit Tests Branch Windows Debug Windows Release Linux main Integration Tests Branch Debug x86 Debug x64 Release x86 Release x64 main Misc Tests Branch Determinism Analyzers Build Correctness Source build TODO/Prototype Spanish MacOS main .NET Foundation This project is part of the .NET Foundation along with other projects like the .NET Runtime.
Read the full README on GitHub

What Hacker News says

32 sources
KirinDave·Dec 11, 2015
Mono is an open source initiative that is not what I was referring to. Please check out https://github.com/dotnet/coreclr and https://github.com/dotnet/roslyn and check the licenses of both. Mono has been lifting large chunks of the MS .NET core libraries over to their implementation because MS has done a lot of work on performance. You can download a Microsoft published source code, and build it, so that you can use the CLR family of languages on Linux and OSX. But none of this has anything to do with cool demos like debugging executables running inside docker. That's a whole different and really cool thing they were working on.
In Report: Microsoft the top-selling tablet maker based on online sales in October
Nelkins·Oct 16, 2015
"Code reviews are described as 'technical debt' and some say this ‘debt’ amounts to a trillion dollars globally." Does anybody else share this view, or is the wording just awkward here? In my experience code reviews help to remove technical debt, rather than accrue it. Their dashboards look nice. Coming from the .NET world, I know that Resharper has had a lot of that kind of functionality as part of its Visual Studio extension [1]. And apparently you can also build your own custom compiler rules for both F# and C#, as both have a compiler-as-a-service[2][3]. I'm sure similar tools exist for other languages as well. [1] https://www.jetbrains.com/resharper/features/code_analysis.h... [2] https://github.com/fsharp/FSharp.Compiler.Service [3] https://github.com/dotnet/roslyn
In Codacy Raises Raises $1.1M to Kill Off Unnecessary Code Reviews
Locke1689·Sep 5, 2015
That's not a "problem" in type inference, that's a design decision where lambda syntax can represent either delegates or expression statements. This is how LINQ-to-SQL can take a LINQ expression and turn it into a SQL statement. However, that doesn't mean we don't wish you wouldn't have to specify the type there -- that's why there's a separate proposal for local functions (https://github.com/dotnet/roslyn/tree/features/local-functio...), which would allow var inc(x) => x + 1;
In C# 7 Proposal: Nullable reference types and nullability checking
WorldMaker·Aug 6, 2015
In my opinion, as such things typically go, it depends on the scope of your tuple usage: I think tuples are perfectly readable/maintainable when used within the context of a single class. It's that middle point between usage within a single method (anonymous types) and usage in the external API (model classes). I try not to leak Tuples between classes: it's easy enough in the API for your class to "unsplat" your tuple usage in any method calls other classes might need. Also, Tuples are likely to become even easier to read/maintain in C#7 or so, as F#-like syntax for Tuples is a strongly favored proposal: https://github.com/dotnet/roslyn/issues/347
In Ask HN: Does the use of Tuples in C# lead to poor code maintainability?

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