May 2, 2026
Paren-t trap on .NET
Dotcl: Common Lisp Implementation on .NET
Old-school coding language crashes the .NET party and the comments instantly spiral
TLDR: dotcl brings the classic Lisp language into Microsoft’s app world, promising one codebase that runs on major computers and phones more easily. Commenters instantly split into benchmark skeptics, rival-project historians, and excited tinkerers already plotting game-engine experiments.
A new project called dotcl is basically trying to pull off a nerdy crossover episode: it lets the famously old-school programming language Common Lisp run inside Microsoft’s modern .NET world, meaning the same code can work across Windows, Mac, and Linux without lots of platform-specific pain. On paper, that’s already a niche dream come true. But in the comments, the real show started: people immediately wanted proof. One of the strongest reactions was the classic internet challenge — okay, but how fast is it? One commenter dragged in F# and even Rust performance comparisons, turning a simple launch post into a mini speed-war before any benchmark chart even hit the stage.
Then came the comedy. One reader joked that “dotcl” sounds like a Lisp spell for interpreting TCL, which is exactly the kind of deeply cursed joke that programming communities adore. Others skipped the speed drama and went straight into “haven’t we seen this before?” mode, name-dropping rivals and predecessors like IronScheme and Bike, giving the whole thread a subtle “love the idea, but where does it fit in the family tree?” vibe.
And of course, the dreamers showed up. The moment people saw a MonoGame sample, the mood shifted from skeptical to chaotic-good: could this thing power Godot or Unity next? Suddenly dotcl wasn’t just a language project — it was a potential weekend rabbit hole. So yes, the launch is about Lisp on .NET. But the comments made it about speed envy, naming jokes, old rivalries, and game-dev fantasies.
Key Points
- •dotcl is a Common Lisp implementation for .NET that compiles Lisp source to CIL and runs on the .NET JIT across Windows, macOS, and Linux on x86-64 and ARM64.
- •The project states broad ANSI Common Lisp compatibility and says it has been verified against the ansi-test suite.
- •dotcl supports embedding Lisp into .NET applications and direct interoperation with .NET types from Lisp, including emitting real .NET subclasses via dotnet:define-class.
- •Initial bootstrap requires Roswell and SBCL plus .NET SDK 10+, after which dotcl can self-host and rebuild its compiler using dotcl itself.
- •The article includes sample integrations for .NET MAUI, ASP.NET Core, MonoGame, and an MCP server exposing a Lisp REPL to clients such as Claude Desktop.