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;;;; License: CC0-1.0
(define-module (net ricketyspace sicp two thirtysix)
#:export (accumulate-n))
(define (accumulate op initial sequence)
(if (null? sequence)
initial
(op (car sequence)
(accumulate op initial (cdr sequence)))))
(define (accumulate-n op init seqs)
(if (null? (car seqs))
'()
(cons (accumulate op init (map (lambda (seq) (car seq)) seqs))
(accumulate-n op init (map (lambda (seq) (cdr seq)) seqs)))))
;;; Guile REPL
;;;
;;; scheme@(guile-user)> ,use (net ricketyspace sicp two thirtysix)
;;; scheme@(guile-user)> (accumulate-n + 0 '((1 2 3) (4 5 6) (7 8 9) (10 11 12)))
;;; $9 = (22 26 30)
;;; scheme@(guile-user)> (accumulate-n + 0 '((2 4 6) (3 6 9) (4 8 12) (5 10 15) (6 12 18)))
;;; $10 = (20 40 60)
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