An Optimizing Compiler for a Purely Functional Web-Application Language

High-level scripting languages have become tremendously popular for development of dynamic Web applications. Many programmers appreciate the productivity benefits of automatic storage manage-ment, freedom from verbose type annotations, and so on. While it is often possible to improve performance substantially by rewrit-ing an application in C or a similar language, very few program-mers bother to do so, because of the consequences for human de-velopment effort. This paper describes a compiler that makes it possible to have most of the best of both worlds, coding Web ap-plications in a high-level language but compiling to native code with performance comparable to handwritten C code. The source language is Ur/Web, a domain-specific, purely functional, stati-cally typed language for the Web. Through a coordinated suite of relatively straightforward program analyses and algebraic op-timizations, we transform Ur/Web programs into almost-idiomatic C code, with no garbage collection, little unnecessary memory al-location for intermediate values, etc. Our compiler is in production use for commercial Web sites supporting thousands of users, and microbenchmarks demonstrate very competitive performance ver-sus mainstream tools