- completer-set! PROCprocedure
Set the completion handler to PROC. PROC is called repeatedly to collect completions with a fixnum state argument and a string prefix. A state argument of zero means that the completion procedure may initialize its data, it is incremented for every subsequent call. The completion procedure must either return a completion matching the given string prefix or #f to signal that no further completions follow. It is up to the completion procedure to keep track of what completions have been offered and whether any further completions are vailable.