1 files changed, 31 insertions, 0 deletions
diff --git a/apps/aux/numbers.scm b/apps/aux/numbers.scm
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+++ b/apps/aux/numbers.scm
@@ -0,0 +1,31 @@
+;;; Harmonic Flow web site
+
+(define-module (apps aux numbers)
+  #:use-module (srfi srfi-1)
+  #:export (minus-one
+	    plus-one
+	    range))
+
+
+(define (minus-one n)
+  "Return N-1."
+  (- n 1))
+
+
+(define (plus-one n)
+  "Return N+1."
+  (+ n 1))
+
+
+(define (range a b)
+  "Return the list of integers in the range [A, B].
+
+   A (integer)
+
+   B (integer)
+
+   RETURN VALUE (list of integers)
+     For example, for the range [-2, 3], return
+     (list -2 -1 0 1 2 3)."
+  (cond ((zero? (- a b)) (cons a (list)))
+	(else (cons a (range (plus-one a) b)))))