It includes
- an extensible syntax (similar to #S)
- conditional reads
- conditional reads based on *features* (similar to #+ and #-)
- stateful block reads (similar to CPP's #if/#elif/#else/#endif)
- lexical read manipulation (e.g. bind *read-base*)
- here documents [fullfilling heredocs in lisp?]
The initial release is available as a tarball or a zipfile.
cl-syntax-sugar is a similar library.