(add-to-load-path (dirname (current-filename)))

(import
    (srfi srfi-41)
    (extra-functional)
    (my-streams))



(define base (stream-from 2))



(define (mark n item)
    (if (eq? (remainder (car item) n) 0)
        (cons (car item) #f)
        item))



(define-stream (sieve input)
    (stream-let loop ((strm (stream-map (part (flip cons) #t) input)))
        (stream-match strm ((item . rest)
            (if (cdr item)
                (stream-cons
                    (car item)
                    (loop (stream-map (part mark (car item)) rest)))
                (loop rest))))))



(define eratosthenes (sieve base))