+
+static int
+scm_default_compare (void const *a, void const *b)
+{
+ SCM pa = *(SCM*) a;
+ SCM pb = *(SCM*) b;
+ if (pa == pb)
+ return 0;
+ return pa < pb ? -1 : 1;
+}
+
+/* Modify LST in place: qsort it. */
+SCM
+ly_list_qsort_uniq_x (SCM lst)
+{
+ int len = scm_ilength (lst);
+ SCM *arr = new SCM[len];
+ int k = 0;
+ for (SCM s = lst; SCM_NNULLP (s); s = SCM_CDR (s))
+ arr[k++] = SCM_CAR (s);
+
+ assert (k == len);
+ qsort (arr, len, sizeof (SCM), &scm_default_compare);
+
+ SCM *tail = &lst;
+ for (int i = 0; i < len; i++)
+ if (!i || arr[i] != arr[i - 1])
+ {
+ SCM_SETCAR (*tail, arr[i]);
+ tail = SCM_CDRLOC (*tail);
+ }
+
+ *tail = SCM_EOL;
+ delete[] arr;
+
+ return lst;
+}
+
+