1 2(define reduce 3 (lambda (op base l) 4 (if (null? l) 5 (begin (browse-environment) base) 6 (op (car l) (reduce op base (cdr l)))))) 7 8(reduce + 0 '(2 3 4)) 9 10(define factit 11 (lambda (n) 12 (letrec 13 ((fit 14 (lambda (n acc) 15 (if (= n 0) 16 (begin 17 (browse-environment) acc) 18 (fit (- n 1) (* n acc)))))) 19 (fit n 1)))) 20 21(factit 6) 22 23(define rec 24 (lambda (n stop) 25 (display n) (newline) 26 (if (= n 0) 27 (begin 28 (browse-environment) 29 (stop 0)) 30 (begin 31 (rec (- n 1) stop) 32 (display n) (newline))))) 33 34(rec 6 (lambda (x) '())) 35