(define (filter p lst)
  (let loop ((lst lst)
             (res '()))
    (cond ((null? lst) (reverse res))
      ((p (car lst)) (loop (cdr lst) (cons (car lst) res)))
      (else (loop (cdr lst) res)))))

(define (any p lst)
  (let loop ((lst lst))
    (cond ((null? lst) #f)
          ((p (car lst)) #t)
          (else (loop (cdr lst))))))

(define (all p lst)
  (let loop ((lst lst))
    (cond ((null? lst) #t)
          ((not (p (car lst))) #f)
          (else (loop (cdr lst))))))

(define (tabulate n proc)
  (let loop ((i 1) (res '()))
    (cond
      ((> i n) res)
      (else (loop (add1 i) (cons (proc) res))))))

(define (filter proc lst)
  (foldl
    (lambda (zero elem)
      (if (proc elem) (cons elem zero) zero))
    '()
    lst))

(define (filter-map proc lst)
  (foldl
    (lambda (zero elem)
      (let ((out (proc elem)))
        (if out (cons out zero) zero)))
    '()
    lst))