chickadee » llrb-tree » binding-set-ref

(binding-set-ref set key [failure] [success])procedure

Extracts the value associated to key in "binding-set", invokes the procedure success on it, and returns its result; if success is not provided, then the value itself is returned. If key is not contained in set and failure is supplied, then failure is invoked on no arguments and its result is returned. Otherwise, it is an error.