[$] Rust's incremental compiler architecture

The traditional structure of a compiler forms a pipeline — parsing,
type-checking, optimization, and code-generation, usually in that order. But
modern programming languages have requirements that are ill-suited to such a
design. Increasingly, compilers are moving toward other designs in
order to support incremental compilation and low-latency responses for uses
like integration into IDEs. Rust has, for the last eight years, been pursuing a
particularly unusual design; in that time
compile times have

substantially improved, but there's still more work to be done.