Elm
Compiler for Elm, a functional language for reliable webapps
... discussions when deciding how to build new projects and making it easy to navigate old or foreign codebases. Enjoy Elm's famously helpful error messages. Even on codebases with hundreds of thousands of lines of code, the compilation is done in a blink. Elm has its own virtual DOM implementation, designed for simplicity and speed. All values are immutable in Elm, and the benchmarks show that this helps us generate particularly fast JavaScript code.