Michael Sperver has written an SRFI that documents "Octet-Addressed Binary Blocks". Basically these things are like BLOBs in SQL: blocks of memory, opaque to the data model of the language, that can be used to store arbitrary binary data. I can think of a bunch of applications for this:
- An internal representation for compiled byte code functions.
- A way to interoperate with C code that expects binary data formats. (Like the Win32 API, for example. )
- A way to represent binary data longer than a byte that's written to and read from binary ports.