chickadee » srfi-116 » ispan

ispan splits the ilist into the longest initial prefix whose elements all satisfy pred, and the remaining tail. ibreak inverts the sense of the predicate: the tail commences with the first element of the input ilist that satisfies the predicate.

In other words: ispan finds the initial span of elements satisfying pred, and ibreak breaks the ilist at the first element satisfying pred.

ispan is equivalent to

(values (itake-while pred ilist)
        (idrop-while pred ilist))

(ispan even? (iq 2 18 3 10 22 9)) =>
  (2 18)
  (3 10 22 9)

(ibreak even? (iq 3 1 4 1 5 9)) =>
  (3 1)
  (4 1 5 9)