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; -- Defs --
(define nil ())
; -- accumulate (equivalent to foldr)
(define (accumulate op initial sequence)
(if (null? sequence)
initial
(op (car sequence)
(accumulate op initial (cdr sequence)))))
; -- define flatmap
(define (flatmap proc seq)
(accumulate append nil (map proc seq)))
; === Display nicely long strings ===
; search index to cut the line.
(define (rec-last-newline s n)
(if (= n 0)
0
(let ((current-car (substring s n (+ n 1))))
(if (string=? "\n" current-car)
n
(rec-last-newline s (- n 1))))))
(define (last-newline s n)
(let ((index (rec-last-newline s n)))
(if (= index 0)
n
index)))
(define (rec-last-special s n)
(if (= n 0)
0
(let ((current-car (substring s n (+ n 1))))
(if (not
(or
(and
(string>=? current-car "A")
(string<=? current-car "Z"))
(and
(string>=? current-car "a")
(string<=? current-car "z"))
(and
(string>=? current-car "0")
(string<=? current-car "9"))
(string=? current-car "-")))
n
(rec-last-special s (- n 1))))))
(define (last-special s n)
(let ((index (rec-last-special s n)))
(if (= index 0)
n
index)))
(define (break-index s n)
(let ((last-special-index (last-special s n))
(last-newline-index (last-newline s n)))
(min last-special-index last-newline-index)))
; wrap naturally a long string to 60 char wide
(define (wrap s)
(if (< (string-length s) 60)
s
(let ((index (break-index s 60)))
(string-append
(substring s 0 index)
(string "\n")
(wrap (substring s (+ index 1) (string-length s))))
)))
; print nicely something (wrap + newline)
(define (print s)
(display (wrap s))(newline))
(define (title s)
(newline)
(display " ")(print s)
(newline))
(define (doc s)
(display "------------------------------------------------------------")
(newline)
(print s)
(display "------------------------------------------------------------")
(newline))
; define seq (useful to count, should be called range)
(define (seq start stop)
(if (> start stop)
(list)
(cons start (seq (+ start 1) stop))))