count[procedure] count pred clist1 clist2 ...
SRFI-1: pred is a procedure taking as many arguments as there
are lists and returning a single value. It is applied element-wise to
the elements of the lists, and a count is tallied of the number of
elements that produce a true value. This count is returned.
count is "iterative" in that it is guaranteed to apply pred to the list
elements in a left-to-right order. The counting stops
when the shortest list expires.
See also fold, reduce.
|