@(define paren)@(maybe)[@(coll)@(paren)@(until)]@(end)]@(end)@(end)
@(do (defvar r (make-random-state nil))

     (defun generate-1 (count)
       (let ((bkt (repeat "[]" count)))
         (cat-str (shuffle bkt))))

     (defun generate-list (num count)
       [[generate tf (op generate-1 count)] 0..num]))
@(next :list @(generate-list 22 6))
@(output)
INPUT           MATCHED         REST
@(end)
@  (collect)
@    (all)
@parens
@    (and)
@{matched (paren)}@mismatched
@    (end)
@  (output)
@{parens 15} @{matched 15} @{mismatched 15}
@  (end)
@(end)