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(functor ((algebraic-structs foldable make) (F (foldl foldr)))
(foldl foldr length find any every ->list)
(import (except scheme length) F
(only (chicken base) add1 call/cc))
(define (length xs)
(foldl (lambda (acc _) (add1 acc))
0
xs))
(define (find p? xs)
(call/cc
(lambda (k)
(foldl (lambda (acc e)
(if (p? e)
(k e)
acc))
#f
xs))))
(define (any pred xs)
(call/cc
(lambda (return)
(foldl (lambda (acc e)
(cond ((pred e) => return)
(else acc)))
#f
xs))))
(define (every pred xs)
(call/cc
(lambda (return)
(foldl (lambda (acc e)
(or (pred e) (return #f)))
#t
xs))))
(define (->list xs)
(foldr cons '() xs)))
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