bytevector-u8-set!

(bytevector-u8-set! bytevector k byte)

Stores byte as element k of bytevector, returning the unspecified value. A byte outside 0-255 is an error (bytevector-u8-set!: not a byte: -1) rather than being truncated. A literal #u8(...) is a fresh bytevector each time it is evaluated, so storing into one does not change the program.