task
Essentially, count the number of occurrences of =={{header| on each task page.

Output:

100 doors: 20 examples.
99 Bottles of Beer: 29 examples.
Abstract type: 10 examples.

Total: X examples.
For a full output, updated periodically, see Rosetta Code/Count examples/Full list.

You'll need to use the Media Wiki API, which you can find out about locally, here, or in Media Wiki's API documentation at, API:Query

use HTTP;
use XML;
 
class RosettaCount {
  function : Main(args : String[]) ~ Nil {
    taks_xml := HttpGet("http://rosettacode.org/mw/api.php?action=query&list=categorymembers&cmtitle=Category:Programming_Tasks&cmlimit=500&format=xml");
    parser := XmlParser->New(taks_xml);    
    if(parser->Parse()) {
      task_names := parser->FindElements("/api/query/categorymembers/cm");
      if(task_names <> Nil) {
        each(i : task_names) {          
          task_name := task_names->Get(i)->As(XmlElement)->GetAttribute("title")->GetValue();
          task_url := "http://rosettacode.org/mw/index.php?title=";
          task_url->Append(task_name);
          task_url->Append("&action=raw");
 
          task := HttpGet(task_url);
          counts := task->FindAll("=={{header|");
          if(counts->Size() > 0) {
            IO.Console->Print(UrlUtility->Decode(task_name))->Print(": ")->PrintLine(counts->Size());
          };
        };
      };
    };
  }
 
  function : HttpGet(url : String) ~ String {
    xml := "";
 
    client := HttpClient->New();
    lines := client->Get(url);
    each(i : lines) {
      xml->Append(lines->Get(i)->As(String));
    };
 
    return xml;
  }
}