grouping.rkt

#lang racket
(require rackunit)

(define (grouping values pred [acc '()])
  (if (empty? values)
      acc
      (let-values ([(taken rest) (splitf-at values pred)])
        (grouping
         (dropf rest (negate pred))
         pred
         (append acc (list taken))))))

(check-equal? '()
              (grouping '() number?))

(check-equal? '((1 2 3))
              (grouping '(1 2 3) number?))


(check-equal? '((1 2 3) (4 5 6))
           (grouping '(1 2 3 null 4 5 6) number?))

(check-equal? '(("a" "b" "c") ("d" "e" "f"))
           (grouping (list
                      "a" "b" "c"
                      ""
                      "d" "e" "f") non-empty-string?))