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Task/Sorting-algorithms-Insertion-sort/Emacs-Lisp/sorting-algorithms-insertion-sort.l

@@ -0,0 +1,44 @@
+(defun min-or-max-of-2-numbers (n1 n2 rel)
+  "n1 and n2 are two numbers, rel can be '< or '> according to
+what sort of sorting is wanted, this function returns the greater
+or smaller number n1 or n2"
+  (cond
+   ((eval (list rel n1 n2)) n1)
+   (t n2)))
+
+(defun min-or-max-of-a-list (lon rel)
+  "lon is a list of numbers, rel is '< or '>, this fonction
+returns the higher or lower number of the list"
+  (if (cdr lon)
+      (min-or-max-of-2-numbers (car lon)
+			       (min-or-max-of-a-list (cdr lon) rel)
+			       rel)
+    (car lon)))
+
+(defun remove-number-from-list (n lon)
+  "lon is a list of numbers, n is a number belonging to the list,
+this function returns the same list but the number n. If n is
+present twice or more, it will be removed only once"
+  (if lon
+      (cond
+       ((= (car lon) n) (cdr lon))
+       (t (cons (car lon) (remove-number-from-list n (cdr lon)))))
+    nil))
+
+
+(defun sort-insertion (lon rel)
+  "lon is a list of numbers, rel can be '< or '>, this function
+returns a list containing the same elements but which is sorted
+according to rel"
+  (if lon
+      (cons (min-or-max-of-a-list lon rel)
+	    (sort-insertion
+	     (remove-number-from-list
+	      (min-or-max-of-a-list lon rel)
+	      lon)
+	     rel))
+    nil))
+
+;;; let's try it :
+
+(sort-insertion (list 1 2 3 9 8 7 25 12 3 2 1) '>)