Extensions

Package-local nicknames

If a string is a "local nickname" for some package A within some other package B, then when *package* is B, find-package (and all implicit uses thereof, e.g. in read) will return A given the string.

Local nicknames are usually specified in defpackage, with the :local-nicknames option. Like so:

(defpackage foo (:use #:cl) (:local-nicknames (#:e #:ext)))

(in-package #:foo)

(e:package-local-nicknames *package*)
; => (("E" . #<PACKAGE EXT>))

"E" in the package prefix means EXT, as long as *package* is the FOO package.

Interface cribbed from SBCL: The :local-nicknames option, and package-local-nicknames, add-package-local-nickname, remove-package-local-nickname, package-locally-nicknamed-by-list. See docstrings.

Extensible sequences

Clasp supports the SEQUENCE extension as described by Dr Christophe Rhodes, which allows standard functions like count to work on user-defined classes, provided they implement a small protocol. The relevant functions are accessible from the SEQUENCE package.

Clasp adds a few helper functions and macros, and as a small deviation from the system as described, does not guarantee that custom methods on sequence:find etc. are called in all situations. It does guarantee that the standard functions and built-in methods will work on general sequences, to be clear, but sometimes optimization opportunities rule out calling the generic function. See src/clos/sequences.lsp for more details.