fork(1) download
copy 
  1. ;; For loops.
  2.  
  3. (use-modules (srfi srfi-1))
  4.  
  5. (define-syntax for
  6.   (syntax-rules (in .. .= by)
  7.     ;; Integer range exclusive by step.
  8.     ((for index in start .. end by step body ...)
  9.      (do ((index start (+ index step))
  10.           (n (ceiling-quotient (- end start) step) (- n 1)))
  11.          ((<= n 0))
  12.          body ...))
  13.     ;; Integer range inclusive by step.
  14.     ((for index in start .= end by step body ...)
  15.      (for index in start .. (+ end (if (negative? step) -1 1)) by step
  16.           body ...))
  17.     ;; Integer range exclusive default step.
  18.     ((for index in start .. end body ...)
  19.      (for index in start .. end by 1
  20.           body ...))
  21.     ;; Integer range inclusive default step.
  22.     ((for index in start .= end body ...)
  23.      (for index in start .= end by 1
  24.           body ...))
  25.     ;; Iterate over a list.
  26.     ((for item in list body ...)
  27.      (for-each (lambda (item)
  28.                  body ...)
  29.                list))))
  30.  
  31. ;; Main.
  32.  
  33. (define (print-range start end step)
  34.   (for i in start .. end by step
  35.        (format #t "~A " i))
  36.   (newline)
  37.   (for i in start .= end by step
  38.        (format #t "~A " i))
  39.   (newline)
  40.   (let ((n (ceiling-quotient (- end start) step)))
  41.     (for i in (iota (max n 0) start step)
  42.          (format #t "~A " i)))
  43.   (newline))
  44.  
  45. (print-range   1   5  1)
  46. (print-range   1  11  2)
  47. (print-range -11  -1  2)
  48. (print-range   5   1 -1)
  49. (print-range  11   1 -2)
  50. (print-range  -1 -11 -2)
  51.  
  52. ;; Nested default step.
  53.  
  54. (for y in 0 .. 4
  55.      (for x in 0 .. 4
  56.           (format #t "[~A ~A] " x y))
  57.      (newline))
Success #stdin #stdout 0.04s 11600KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
1 2 3 4 
1 2 3 4 5 
1 2 3 4 
1 3 5 7 9 
1 3 5 7 9 11 
1 3 5 7 9 
-11 -9 -7 -5 -3 
-11 -9 -7 -5 -3 -1 
-11 -9 -7 -5 -3 
5 4 3 2 
5 4 3 2 1 
5 4 3 2 
11 9 7 5 3 
11 9 7 5 3 1 
11 9 7 5 3 
-1 -3 -5 -7 -9 
-1 -3 -5 -7 -9 -11 
-1 -3 -5 -7 -9 
[0 0] [1 0] [2 0] [3 0] 
[0 1] [1 1] [2 1] [3 1] 
[0 2] [1 2] [2 2] [3 2] 
[0 3] [1 3] [2 3] [3 3]
https://ideone.com/KHM1U6
language:
Scheme (guile 2.2.4)
created:
13 days ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!