Welcome to the CHICKEN Scheme pasting service

(define foo
  (recursive-parser (sequence (any-of (is #\a)
                                      foo)
                              (is #\b))))

(parse foo "abb")

;; Expected output:
;; ((#\a #\b) #\b)
;; #<parser-input-end>

;; Actual output:
;; (#\a #\b)
;; #<parser-input char-seq-cursor "b" ...>