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A Common Lisp implementation of the MessagePack (http://msgpack.org/) serialization/deserialization format, implemented according to http://wiki.msgpack.org/display/MSGPACK/Format+specification.

Depends on flexi-streams and babel. Floating point values are supported only on SBCL currently.

Status: first draft encoder and decoder implemented, added extensions for some Lisp data types (see below), simple tests.

A 'pure' cons is a cons whose CDR is not a cons. Regular lists are encoded as Message Pack arrays, but we need something special for conses.

The pure cons is encoded as byte #xC4, followed by the encodings of the CAR of the cons and the encoding of the CDR of the cons.

In order to be able to restore the symbols as symbols, we can't simply encode them as strings. So a symbol will be encoded as byte #xC5, followed by the name of the package of the symbol, followed by the name of the symbol.

Since encoding symbols should be shorter than encoding strings, we can encode them as numbers, provided that the encoder and decoder both have knowledge of a symbol <-> integer bijection between the symbols and the numbers. A symbol that is found in this table will be encoded as byte #xC6, followed by the encoding of its corresponding integer.

Rationals are encoded as byte #xC7, followed by the encoding of the numerator, and the encoding of the denominator. If the numerator cannot be encoded as an integer (it is too large to be encoded as an uint64 or an int64, it will be encoded as a string. The same happens for large denominators).

Copy the cl-messagepack directory to the local-projects directory of your Quicklisp install, then

(require :cl-messagepack)
(fiveam:run! 'mpk-tests::cl-messagepack-tests)

in a REPL (tested under SBCL and CCL under Linux x64).