case of DEFINE-ERRNO-SYSCALL. However, this change causes simple errno syscalls to return 0 values, which blows up I/O methods used in S48's extensible port system, so I had to hack three or four of those methods to return a random value (#F).
LET-OPTIONAL, LET-OPTIONAL*, and :OPTIONAL. The new macros are faster and easier to read than the old PARSE-OPTIONALS and OPTIONAL-ARG procedures.