Racket 6.6 发布，更新如下：
The new Macro Profiler command-line tool (`raco macro-profiler`) shows how macros contribute to the final expanded code size of a program.
Typed Racket supports intersection types. This allows the type system to track more information, and for programmers to express more precise types.
Typed Racket produces up to 4x smaller compiled files compared with Racket 6.5, reducing the size of the Racket distribution by 50M.
Typed Racket issues warnings in cases where the contract generated for Any was not strict enough in the past. These warnings will become errors in a future release. Warnings are enabled via View -> Show Log in DrRacket, and shown by default on command-line Racket.
Typed Racket enforces uses of cast more correctly, by checking both the "casted-to" and "casted-from" types. Previously, only the former were checked. In some cases, this will produce contract errors in programs that did not have errors before.
syntax-parse raises an error when an ellipsis pattern has an empty match rather than diverging, and it logs a warning when it statically detects a nullable pattern, such as((~seq) ...). In the next version of Racket, it will reject the pattern instead, and it will remove special handling that currently makes some uses of such patterns terminate.
htdp/dir: The create-dir function delivers data information for files in a new field. The domain of its functions are backwards compatible.