July 20, 2015
C# 6 and Roslyn compiler released
Visual StudioMicrosoft's IDE — editing, debugging, and profiling for .NET, C++, and web projects. 2015 shipped on July 20, 2015 with C# 6 and the open-source Roslyn compiler platform — bringing string interpolation, null-conditional operators, and analyzers.
What it was for
Roslyn exposed C# as an APIApplication programming interface — a defined way for programs to talk to each other or to a service.: IDEs, linters, and code generators could parse and rewrite syntax trees. C# 6's `$"Hello {name}"` and `obj?.Method()` reduced boilerplate. The compiler-as-a-library model influenced .NET tooling for a decade.
Companies
- Microsoft
Why it's here
Roslyn turned the C# compiler into extensible infrastructure for the whole .NET ecosystem.
Why it mattered
Open-sourcing the compiler enabled analyzers, source generators, and cross-platform builds.
What it solved
Closed compilers blocked third-party refactoringRestructuring code without changing behavior — improving design while keeping tests green. tools and language experimentation.
Media
- ImageC Sharp (programming language)
Microsoft, Public domain, via Wikimedia Commons
Related
- .NET 4.5 and C# 5.0 with async/await releasedAugust 15, 2012
- .NET 6 LTS releasedNovember 8, 2021