Sort stability: Difference between revisions

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 Oz' [http://www.mozart-oz.org/home/doc/base/list.html#label295 Sort] function is not guaranteed to be stable in the documentation.
-However, it uses mergesort and in practice ''is'' stable '''if''' a reflexive ordering is used, e.g. <code>Value.'=<'</code> or <code>Value.'>='</code>.
+However, internally it uses [[Merge sort]] and in practice ''is'' stable '''if''' a reflexive ordering is used, e.g. <code>Value.'=<'</code> or <code>Value.'>='</code>.
+Example:
+<lang oz>declare
+  Cities = ['UK'#'London'
+            'US'#'New York'
+            'US'#'Birmingham'
+            'UK'#'Birmingham']
+in
+  %% sort by city; stable because '=<' is reflexiv
+  {Show {Sort Cities fun {$ A B} A.2 =< B.2 end}}
+  %% sort by country; NOT stable because '<' is not reflexiv
+  {Show {Sort Cities fun {$ A B} A.1 < B.1 end}}</lang>
 =={{header|Perl}}==