The PACKER binary format library implements a "little language" for C-style structures, along the lines of Perl's pack() or Python's struct module. It is similar in spirit to Binary-types, although much less general. Version 0.2 is a near-complete rewrite and offers portable packing and unpacking (of SINGLE-FLOAT and DOUBLE-FLOATs as well) and a more obviously extensible packing protocol.