Rosetta Code/Find unimplemented tasks

From Rosetta Code
Rosetta Code/Find unimplemented tasks
You are encouraged to solve this task according to the task description, using any language you may know.

Given the name of a language on Rosetta Code, find all tasks which are not implemented in that language.

Note: Implementations should allow for fetching more data than can be returned in one request to Rosetta Code.

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


Library: AWS

Parsing XML with XMLAda from Adacore

with Aws.Client, Aws.Messages, Aws.Response, Aws.Resources, Aws.Url;
with Dom.Readers, Dom.Core, Dom.Core.Documents, Dom.Core.Nodes, Dom.Core.Attrs;
with Input_Sources.Strings, Unicode, Unicode.Ces.Utf8;
with Ada.Strings.Unbounded, Ada.Text_IO, Ada.Command_Line;
with Ada.Containers.Vectors;
use Aws.Client, Aws.Messages, Aws.Response, Aws.Resources, Aws.Url;
use Dom.Readers, Dom.Core, Dom.Core.Documents, Dom.Core.Nodes, Dom.Core.Attrs;
use Aws, Ada.Strings.Unbounded, Input_Sources.Strings;
use Ada.Text_IO, Ada.Command_Line;
procedure Not_Coded is
package Members_Vectors is new Ada.Containers.Vectors (
Index_Type => Positive,
Element_Type => Unbounded_String);
use Members_Vectors;
All_Tasks, Language_Members : Vector;
procedure Get_Vector (Category : in String; Mbr_Vector : in out Vector) is
Reader : Tree_Reader;
Doc  : Document;
List  : Node_List;
N  : Node;
A  : Attr;
Page  : Aws.Response.Data;
S  : Messages.Status_Code;
-- Query has cmlimit value of 100, so we need 5 calls to
-- retrieve the complete list of Programming_category
Uri_Xml  : constant String  :=
Cmcontinue : Unbounded_String := Null_Unbounded_String;
Page :=
Aws.Client.Get (Uri_Xml & Category & (To_String (Cmcontinue)));
S  := Response.Status_Code (Page);
if S not in Messages.Success then
("Unable to retrieve data => Status Code :" &
Image (S) &
" Reason :" &
Reason_Phrase (S));
raise Connection_Error;
end if;
Xml  : constant String := Message_Body (Page);
Source : String_Input;
Parse (Reader, Source);
Close (Source);
Doc  := Get_Tree (Reader);
List := Get_Elements_By_Tag_Name (Doc, "cm");
for Index in 1 .. Length (List) loop
N := Item (List, Index - 1);
A := Get_Named_Item (Attributes (N), "title");
To_Unbounded_String (Value (A)));
end loop;
Free (List);
List := Get_Elements_By_Tag_Name (Doc, "query-continue");
if Length (List) = 0 then
-- we are done
Free (List);
Free (Reader);
end if;
N  := First_Child (Item (List, 0));
A  := Get_Named_Item (Attributes (N), "cmcontinue");
Cmcontinue :=
("&cmcontinue=" & Aws.Url.Encode (Value (A)));
Free (List);
Free (Reader);
end loop;
end Get_Vector;
procedure Quick_Diff (From : in out Vector; Substract : in Vector) is
Beginning, Position : Extended_Index;
-- take adavantage that both lists are already sorted
Beginning := First_Index (From);
for I in First_Index (Substract) .. Last_Index (Substract) loop
Position :=
(Container => From,
Item => Members_Vectors.Element (Substract, I),
Index => Beginning);
if not (Position = No_Index) then
Delete (From, Position);
Beginning := Position;
end if;
end loop;
end Quick_Diff;
if Argument_Count = 0 then
Put_Line ("Can't process : No language given!");
Get_Vector (Argument (1), Language_Members);
end if;
Get_Vector ("Programming_Tasks", All_Tasks);
Quick_Diff (All_Tasks, Language_Members);
for I in First_Index (All_Tasks) .. Last_Index (All_Tasks) loop
Put_Line (To_String (Members_Vectors.Element (All_Tasks, I)));
end loop;
("Numbers of tasks not implemented :=" &
Integer'Image (Last_Index ((All_Tasks))));
end Not_Coded;


The GUI overkill version with comments.

#NoEnv ; do not resolve environment variables (speed)
#SingleInstance force ; allow only one instance
SetBatchLines, -1 ; set to highest script speed
SetControlDelay, 0 ; set delay between control commands to lowest
; additional label, for clarity only
Gui, Add, DDL, x10 y10 w270 r20 vlngStr ; add drop-down list
Gui, Add, Button, x290 y10 gShowLng, Show Unimplemented ; add button
Gui, Add, ListView, x10 y36 w400 h300 vcatLst gOnLV, Unimplemented ; add listview
Gui, Add, StatusBar, vsbStr, ; add statusbar
Gui, Show, , RosettaCode unimplemented list ; show the gui
allLng := getList("lng") ; get a list of all available languages
selectStr = Select language... ; set selection string for ddl
GuiControl, , LngStr, |%selectStr%||%allLng% ; set the ddl to new contents
SB_SetIcon("user32.dll", 5) ; change statusbar icon
SB_SetText("Done loading languages. Select from menu.") ; change statusbar text
Return ; end of the autoexec section. Script waits for input.
; subroutine for language list in ddl update
Gui, Submit, NoHide ; refresh all gui variables
If (lngStr != selectStr) ; if the current selected language is not the selection string
SB_SetIcon("user32.dll", 2) ; set statusbar icon to exclamation
SB_SetText("Loading unimplemented tasks... Please wait.") ; set statusbar text
allTsk := getList("tsk") ; get a list of all tasks
allThis := getList(lngStr) ; get a list of all done tasks for this language
Loop, Parse, allTsk, | ; parse the list of all tasks
If !InStr(allThis,A_LoopField) ; if the current task is not found in the list of all tasks
notImpl .= A_LoopField . "|" ; add the current field to the notImpl variable
allTskCnt := A_Index ; save the index for final count
StringTrimRight, notImpl, notImpl, 1 ; remove last delimiter
LV_Delete() ; emty the listview
GuiControl, -Redraw, catLst ; set the listview to not redraw while adding (speed)
Loop, Parse, notImpl, | ; parse the list of not implemented tasks
LV_Add("", A_LoopField) ; add them to the listview, field by field
notImplCnt := A_Index ; save the index for final count
GuiControl, +Redraw, catLst ; set the listview back to normal
SB_SetIcon("user32.dll", 5) ; change statusbar icon to information
SB_SetText("There are " . notImplCnt . " of " . allTskCnt
. " tasks unimplemented. Double-click task to open in browser.") ; set the statusbar text
notImpl = ; empty the notImpl variable
notImplCnt = 0 ; set the count back to 0
; subroutine for action on listview
If (A_GuiEvent = "DoubleClick") ; if the listview was double-clicked
LV_GetText(rowTxt, A_EventInfo) ; get the text of the clicked row
rowTxt := Enc_Uri(rowTxt) ; uri-encode the text
StringReplace, rowTxt, rowTxt, `%20, _, All ; replace all space-encodings with underscores
Run % "" . rowTxt ; run the resulting link in the default browser
; generic function to gather list
fileName = temp.xml ; set temp-file name
If (category = "lng") ; if the category received is lng
category = Programming_Languages ; set the category
fileName = lng.xml ; set temp-file name
IfExist, %fileName% ; if the file already exists
FileGetTime, modTime, %fileName% ; get the last modified time
EnvSub, modTime, %A_Now%, days ; get the difference between now and last modified time in days
If (modTime < 3) ; if the result is less than 3
Goto, GetFileNoDL ; go to function-internal subroutine to parse
SB_SetIcon("user32.dll", 2) ; set statusbar icon
SB_SetText("Loading languages... Please wait.") ; set statusbar text
If (category = "tsk") ; if the category received is tsk
category = Programming_Tasks ; set the category
getFile: ; function-internal subroutine for getting a file and parsing it
; construct the url
url := ""
. "categorymembers&cmtitle=Category:" . category
. "&cmlimit=500&format=xml" . doContinue
UrlDownloadToFile, %url%, %fileName% ; download the url
getFileNoDL: ; function-internal subroutine for parsing a file
FileRead, data, %fileName% ; read file into variable
pos = 1 ; set while-loop counter
rxp = title="(.*?)" ; set regular expression
While (pos := RegExMatch(data, rxp, title, pos)) ; get the contents of the title fields one-by-one
If InStr(title1, "Category:") ; if the contents contain Category:
StringTrimLeft, title1, title1, 9 ; remove that from the contents
StringReplace, title1, title1, |, `|, All ; escape all containing delimiters
title1 := Dec_XML(UTF82Ansi(title1)) ; convert to ansi first and then decode html entities
allTitles .= title1 . "|" ; add this title to list
pos++ ; increment counter
rxp = cmcontinue="(.*?)" ; set regular expression
If RegExMatch(data, rxp, next) ; when found
doContinue = &cmcontinue=%next1% ; set continuation string to add to url
Goto getFile ; go to function-internal subroutine to redownload and parse
StringTrimRight, allTitles, allTitles, 1 ; remove last delimiter from result
Return allTitles ; return result
; function to convert html entities to ansi equivalents
If RegexMatch(str, "S)(&#(\d+);)", dec)
StringReplace, str, str, %dec1%, % Chr(dec2), All
Else If RegexMatch(str, "Si)(&#x([\da-f]+);)", hex)
StringReplace, str, str, %hex1%, % Chr("0x" . hex2), All
StringReplace, str, str, &nbsp;, %A_Space%, All
StringReplace, str, str, &quot;, ", All
StringReplace, str, str, &apos;, ', All
StringReplace, str, str, &lt;, <, All
StringReplace, str, str, &gt;, >, All
StringReplace, str, str, &amp;, &, All
return, str
; function to uri-encode input string
f = %A_FormatInteger%
SetFormat, Integer, Hex
If RegExMatch(str, "^\w+:/{0,2}", pr)
StringTrimLeft, str, str, StrLen(pr)
StringReplace, str, str, `%, `%25, All
If RegExMatch(str, "i)[^\w\.~%/:]", char)
StringReplace, str, str, %char%, % "%" . SubStr(Asc(char),3), All
Else Break
SetFormat, Integer, %f%
Return, pr . str
; function to convert unicode to ansi text
Ansi2Unicode(zString, wString, 65001)
Unicode2Ansi(wString, sString, 0)
Return sString
; helper function for unicode to ansi function
Ansi2Unicode(ByRef sString, ByRef wString, CP = 0)
nSize := DllCall("MultiByteToWideChar", "Uint", CP
, "Uint", 0, "Uint", &sString, "int", -1
, "Uint", 0, "int", 0)
VarSetCapacity(wString, nSize * 2)
, "Uint", CP, "Uint", 0, "Uint", &sString, "int", -1
, "Uint", &wString, "int", nSize)
; helper function for unicode to ansi function
Unicode2Ansi(ByRef wString, ByRef sString, CP = 0)
nSize := DllCall("WideCharToMultiByte"
, "Uint", CP, "Uint", 0, "Uint", &wString, "int", -1
, "Uint", 0, "int", 0, "Uint", 0, "Uint", 0)
VarSetCapacity(sString, nSize)
, "Uint", CP, "Uint", 0, "Uint", &wString, "int", -1
, "str", sString, "int", nSize, "Uint", 0, "Uint", 0)
; subroutine called when user closes the gui
ExitApp ; exit the script


Loads a list of all languages. Pick the language you would like to see the unimplemented tasks of, press the button, double click the selected task to launch in default browser. It will download the languages to file and redownload if older than 3 days (to save unnecessary bandwith).

Ahk find unimplemented.png


Using JSON (not parsed, just Regex.)

To help demonstrate paging, the cmlimit parameter has been omitted from the search query so that 10 rows are returned by default

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Net;
class Program {
static List<string> GetTitlesFromCategory(string category) {
string searchQueryFormat = "{0}&format=json{1}";
List<string> results = new List<string>();
string cmcontinue = string.Empty;
do {
string cmContinueKeyValue;
//append continue variable as needed
if (cmcontinue.Length > 0)
cmContinueKeyValue = String.Format("&cmcontinue={0}", cmcontinue);
cmContinueKeyValue = String.Empty;
//execute query
string query = String.Format(searchQueryFormat, category, cmContinueKeyValue);
string content = new WebClient().DownloadString(query);
results.AddRange(new Regex("\"title\":\"(.+?)\"").Matches(content).Cast<Match>().Select(x => x.Groups[1].Value));
//detect if more results are available
cmcontinue = Regex.Match(content, @"{""cmcontinue"":""([^""]+)""}", RegexOptions.IgnoreCase).Groups["1"].Value;
} while (cmcontinue.Length > 0);
return results;
static string[] GetUnimplementedTasksFromLanguage(string language) {
List<string> alltasks = GetTitlesFromCategory("Programming_Tasks");
List<string> lang = GetTitlesFromCategory(language);
return alltasks.Where(x => !lang.Contains(x)).ToArray();
static void Main(string[] args) {
string[] unimpl = GetUnimplementedTasksFromLanguage(args[0]);
foreach (string i in unimpl) Console.WriteLine(i);


This uses a couple of core libraries, and a Java method for URL encoding.

'[clojure.xml :as xml]
'[clojure.set :as set]
'[clojure.string :as string])
(import '[ URLEncoder])

The titles-cont function fetches and parses an XML response, and walks over it extracting titles. It also extracts the cmcontinue value, if present. Returns a pair [titles,cmcontinue].

(defn titles-cont [url]
(let [docseq (-> url xml/parse xml-seq)]
((juxt #(filter string? %), #(-> (filter map? %) first :cmcontinue))
(for [{:keys [tag attrs content]} docseq :when (#{:cm :query-continue} tag)]
(if (= tag :cm)
(attrs :title)
(-> content first :attrs))))))

The get-titles function has 1- and 2-argument versions. The former takes the name of a category, composes the appropriate URL query, and calls the 2-argument version. The 2-argument version gets a title list (with possible cmcontinue value), chaining further calls as necessary into the lazy sequence result.

(defn urlencode [s] (URLEncoder/encode s "UTF-8"))
(defn param [p v] (str p (urlencode v)))
(defn get-titles
(let [urlbase ""
params ["action=query"
(param "cmtitle=Category:" category)]
url (str urlbase "?" (string/join "&" params)]
(get-titles url nil)))
([url continue-at]
(let [continue-param (if continue-at (param "&cmcontinue=" continue-at))
[titles continue] (titles-cont (str url continue-param))]
(if continue
(lazy-cat titles (get-titles url continue))

The unimplemented function gets a set of all titles and of language-implemented titles and returns the difference. It uses future in order to do the necessary URL requests in parallel.

(defn unimplemented [lang-name]
(let [title-set #(future (apply sorted-set (get-titles %)))
all-titles (title-set "Programming_Tasks")
lang-titles (title-set lang-name)]
(seq (set/difference @all-titles @lang-titles))))
(let [titles (unimplemented "Clojure")]
(doseq [title titles] (println title))
(println "count: " (count titles)))


Using JSON.

#!/usr/bin/env rune
# NOTE: This program will not work in released E, because TermL is an
# imperfect superset of JSON in that version: it does not accept "\/".
# If you build E from the latest source in SVN then it will work.
# Usage: rosettacode-cat-subtract.e [<lang e>]
# Prints a list of tasks which have not been completed in the language.
# If unspecified, the default language is E.
def termParser := <import:org.quasiliteral.term.makeTermParser>
def jURLEncoder := <>
def urlEncode(text) {
return jURLEncoder.encode(text, "UTF-8")
/** Convert JSON-as-term-tree to the corresponding natural E data structures. */
def jsonTermToData(term) {
switch (term) {
# JSON object to E map
match term`{@assocs*}` {
return accum [].asMap() for term`@{key :String}: @valueJson` in assocs {
_.with(key, jsonTermToData(valueJson))
# JSON array to E list
match term`[@elements*]` {
return accum [] for elem in elements { _.with(jsonTermToData(elem)) }
# Literals just need to be coerced
match lit :any[String, int, float64] {
return lit
# Doesn't support true/false/null, but we don't need that for this application.
def fetchCategoryAccum(name, membersSoFar :Set, extraArgs) {
stderr.println(`Fetching Category:$name $extraArgs...`)
def categoryAPIResource := <http>[`//` +
`action=query&list=categorymembers&cmtitle=Category:${urlEncode(name)}&` +
def members :=
when (def responseJSON := categoryAPIResource <- getTwine()) -> {
# stderr.println(`Fetched Category:$name $extraArgs, parsing...`)
def response := jsonTermToData(termParser(responseJSON))
# stderr.println(`Parsed Category:$name $extraArgs response, extracting data...`)
def [
"query" => ["categorymembers" => records],
"query-continue" => continueData := null
] := response
def members := accum membersSoFar for record in records { _.with(record["title"]) }
switch (continueData) {
match ==null {
stderr.println(`Got all ${members.size()} for Category:$name.`)
match ["categorymembers" => ["cmcontinue" => continueParam]] {
stderr.println(`Fetched ${members.size()} members for Category:$name...`)
fetchCategoryAccum(name, members, `&cmcontinue=` + urlEncode(continueParam))
} catch p { throw(p) }
return members
def fetchCategory(name) {
return fetchCategoryAccum(name, [].asSet(), "")
# Interpret program arguments
def lang := switch (interp.getArgs()) {
match [lang] { lang }
match [] { "E" }
# Fetch categories
when (def allTasks := fetchCategory("Programming_Tasks"),
def doneTasks := fetchCategory(lang),
def omitTasks := fetchCategory(lang + "/Omit")
) -> {
# Compute difference and report
def notDoneTasks := allTasks &! (doneTasks | omitTasks)
} catch p {
# Whoops, something went wrong


init_http/0 is used by many tasks. rosetta_code_list_of/1 is used by Rosetta_Code/Rank_languages_by_popularity

-module( find_unimplemented_tasks ).
-include_lib( "xmerl/include/xmerl.hrl" ).
-export( [init_http/0, per_language/1, rosetta_code_list_of/1] ).
init_http() ->
application:start( inets ).
per_language( Language ) ->
ok = init_http(),
Tasks = rosetta_code_list_of( "Programming_Tasks" ),
Uninplemented = Tasks -- rosetta_code_list_of( Language ),
io:fwrite( "Unimplemented total: ~p~n", [erlang:length(Uninplemented)] ),
[io:fwrite("~p~n", [X]) || X <- Uninplemented].
rosetta_code_list_of( Category ) ->
URL = ""
++ Category,
title_contents( URL, "", [] ).
title_contents( URL, Continue, Acc ) ->
{ok, {{_HTTP,200,"OK"}, _Headers, Body}} = httpc:request( URL ++ Continue ),
{XML, _} = xmerl_scan:string( Body ),
News = xml_selection( "title", XML ),
New_continue = title_contents_url_continue( xml_selection("cmcontinue", XML) ),
title_contents_continue( URL, New_continue, Acc ++ News ).
title_contents_continue( _URL, "", Acc ) -> Acc;
title_contents_continue( URL, Continue, Acc ) -> title_contents( URL, Continue, Acc ).
title_contents_url_continue( [] ) -> "";
title_contents_url_continue( [Continue | _] ) -> "&cmcontinue=" ++ Continue.
xml_selection( Selection, XML ) ->
[lists:map( fun xml_8211/1, X) || #xmlAttribute{value=X} <- xmerl_xpath:string("//@" ++ Selection, XML)].
xml_8211( 8211 ) -> $-;
xml_8211( 924 ) -> $\s;
xml_8211( 1050 ) -> $\s;
xml_8211( 1052 ) -> $\s;
xml_8211( Character ) -> Character.
25> find_unimplemented_tasks:per_language("Erlang").
Unimplemented total: 307
"24 game/Solve"
"Abstract type"
"Active Directory/Search for a user"
"Add a variable to a class instance at runtime"
"Address of a variable"
"Yahoo! search interface"
"Yin and yang"
"Zeckendorf arithmetic"
"Zeckendorf number representation"
"Zhang-Suen thinning algorithm"


XML, stepping through the elements.

package main
import (
const language = "Go"
var baseQuery = "" +
func req(u string, foundCm func(string)) string {
resp, err := http.Get(u)
if err != nil {
fmt.Println(err) // connection or request fail
return ""
defer resp.Body.Close()
for p := xml.NewDecoder(resp.Body); ; {
t, err := p.RawToken()
switch s, ok := t.(xml.StartElement); {
case err == io.EOF:
return ""
case err != nil:
return ""
case !ok:
case s.Name.Local == "cm":
for _, a := range s.Attr {
if a.Name.Local == "title" {
case s.Name.Local == "categorymembers" && len(s.Attr) > 0 &&
s.Attr[0].Name.Local == "cmcontinue":
return url.QueryEscape(s.Attr[0].Value)
return ""
func main() {
// get language members, store in a map
langMap := make(map[string]bool)
storeLang := func(cm string) { langMap[cm] = true }
languageQuery := baseQuery + "&cmtitle=Category:" + language
continueAt := req(languageQuery, storeLang)
for continueAt > "" {
continueAt = req(languageQuery+"&cmcontinue="+continueAt, storeLang)
// a quick check to avoid long output
if len(langMap) == 0 {
fmt.Println("no tasks implemented for", language)
// get tasks, print as we go along
printUnImp := func(cm string) {
if !langMap[cm] {
taskQuery := baseQuery + "&cmtitle=Category:Programming_Tasks"
continueAt = req(taskQuery, printUnImp)
for continueAt > "" {
continueAt = req(taskQuery+"&cmcontinue="+continueAt, printUnImp)


Library: HTTP XML
from HackageDB
import Network.Browser
import Network.HTTP
import Network.URI
import Data.List
import Data.Maybe
import Text.XML.Light
import Control.Arrow
import Data.Char
getRespons url = do
rsp <- Network.Browser.browse $ do
setAllowRedirects True
setOutHandler $ const (return ()) -- quiet
request $ getRequest url
return $ rspBody $ snd rsp
replaceWithSpace c = (\x -> if c==x then ' ' else x)
encl = chr 34
unimpTasks lang = do
allTasks <- getRespons ""
impl <- getRespons ( "" ++ lang ++ ".json")
let langxx = map (map(replaceWithSpace '_')) $ filter (/=",") $ words $ map (replaceWithSpace encl ) $ init $ drop 1 impl
xml = onlyElems $ parseXML allTasks
allxx = concatMap (map (fromJust.findAttr (unqual "title")). filterElementsName (== unqual "cm")) xml
mapM_ putStrLn $ sort $ allxx \\ langxx

With only standard libraries

import Network.HTTP
import Data.Text (splitOn, pack, unpack)
import Data.List
getTasks :: String -> IO [String]
getTasks url = do
resp <- simpleHTTP (getRequest url)
body <- getResponseBody resp
return $ tail $ map (unpack . head . splitOn (pack "\"}")) $ splitOn (pack "\"title\":\"") (pack body)
main :: String -> IO ()
main lang = do
implTasks <- getTasks $ "" ++ lang ++ "&format=json&cmlimit=500"
allTasks <- getTasks ""
mapM_ putStrLn $ allTasks \\ implTasks

Icon and Unicon[edit]

The following code only works in Unicon.

$define RCINDEX ""
$define RCTASK ""
$define RCUA "User-Agent: Unicon Rosetta 0.1"
$define RCXUA "X-Unicon:"
$define TASKTOT "* Total Tasks *"
$define TOTTOT "* Total Headers*"
link strings
link hexcvt
procedure main(A) # simple single threaded read all at once implementation
lang := \A[1] | "Unicon"
write("Unimplemented tasks for ",lang," as of ",&date)
every task := taskNames() do {
if lang == languages(task) then next
# Generate task names
procedure taskNames()
continue := ""
while \(txt := ReadURL(RCINDEX||continue)) do {
txt ? {
while tab(find("<cm ") & find(s :="title=\"")+*s) do
suspend tab(find("\""))\1
if tab(find("cmcontinue=")) then {
continue := "&"||tab(upto(' \t'))
else break
# Generate language headers in a task
procedure languages(task)
static WS
initial WS := ' \t'
page := ReadURL(RCTASK||CleanURI(task))
page ? while (tab(find("\n==")),tab(many(WS))|"",tab(find("{{"))) do {
header := tab(find("=="))
header ? {
while tab(find("{{header|")) do {
suspend 2(="{{header|",tab(find("}}")))\1
procedure CleanURI(u) #: clean up a URI
static tr,dxml # xml & http translation
initial {
tr := table()
every c := !string(~(&digits++&letters++'-_.!~*()/\'`')) do
tr[c] := "%"||hexstring(ord(c),2)
every /tr[c := !string(&cset)] := c
tr[" "] := "_" # wiki convention
every push(dxml := [],"&#"||right(ord(c := !"&<>'\""),3,"0")||";",c)
dxml[1] := u # insert URI as 1st arg
u := replacem!dxml # de-xml it
every (c := "") ||:= tr[!u] # reencode everything
c := replace(c,"%3E","'") # Hack to put single quotes back in
c := replace(c,"%26quot%3B","\"") # Hack to put double quotes back in
return c
procedure ReadURL(url) #: read URL into string
page := open(url,"m",RCUA,RCXUA) | stop("Unable to open ",url)
text := ""
if page["Status-Code"] < 300 then while text ||:= reads(page,-1)
else write(&errout,image(url),": ",
page["Status-Code"]," ",page["Reason-Phrase"])
return text

Sample output (abridged):

Unimplemented tasks for Unicon as of 2013/07/06:
Y combinator
Zebra puzzle
Zeckendorf arithmetic
Zeckendorf number representation



require 'strings web/gethttp'
findUnimpTasks=: ('Programming_Tasks' -.&getCategoryMembers ,&'/Omit') ([ #~ [email protected]) getCategoryMembers
getTagContents=: dyad define
'starttag endtag'=. x
('\' -.~ endtag&taketo)&.>@(starttag&E. <@((#starttag)&}.);.1 ]) y
NB. RosettaCode Utilities
parseTitles=: ('"title":"';'"')&getTagContents
getCMcontquery=: ('&cmcontinue=' , urlencode)^:(0 < #)@>@parseCMcontinue
getCategoryMembers=: monad define
buildqry=. 'action=query&list=categorymembers&cmtitle=Category:' , ,&'&cmlimit=500&format=json'
uri=. url ,'?', buildqry urlencode y
catmbrs=. qrycont=. ''
whilst. #qrycont=. getCMcontquery jsondat do.
jsondat=. gethttp uri , qrycont
catmbrs=. catmbrs, parseTitles jsondat

Example Usage:

   4{. findUnimpTasks 'J'     NB. get first 4 unimplemented tasks for J
|Active object|Atomic updates|Basic input loop|Call foreign language function|


The isolation of in-browser JavaScript from system resources, and the association of JavaScript code files with particular (and already loaded) documents may mean that JavaScript is not the right tool for the broader case envisaged by this task.

For the narrower context of a browser in which the 'not implemented' page has been fetched for a particular language, we can however, evaluate an XPath expression in JavaScript to generate an array of titles for the unimplemented tasks.

(function (strXPath) {
var xr = document.evaluate(
null, 0, 0
oNode = xr.iterateNext(),
lstTasks = [];
while (oNode) {
oNode = xr.iterateNext();
return [
lstTasks.length + " items found in " + document.title,

Output begins with:

107 items found in Reports:Tasks not implemented in Haskell - Rosetta Code

Active Directory/Connect
Active Directory/Search for a user
Bitmap/Bézier curves/Cubic
Bitmap/PPM conversion through a pipe
Bitmap/Read an image through a pipe
Call a function in a shared library
Call an object method
Canny edge detector
Casting out nines
Catmull–Clark subdivision surface
Color of a screen pixel
Colour bars/Display
Colour pinstripe/Display
Colour pinstripe/Printer
Compare sorting algorithms' performance
Conjugate transpose
Create a file on magnetic tape
Death Star
Executable library
Extreme floating point values
Fibonacci word/fractal
Find limit of recursion


using HTTP, JSON
const baseuri = ""
const enduri = "&cmlimit=500&format=json"
queries(x) = baseuri * HTTP.Strings.escapehtml(x) * enduri
function getimplemented(query)
tasksdone = Vector{String}()
request = query
while (resp = HTTP.request("GET", request)).status == 200
fromjson = JSON.parse(String(resp.body))
for d in fromjson["query"]["categorymembers"]
if haskey(d, "title")
push!(tasksdone, d["title"])
if haskey(fromjson, "continue")
cmcont, cont = fromjson["continue"]["cmcontinue"], fromjson["continue"]["continue"]
request = query * "&cmcontinue=$cmcont&continue=$cont"
alltasks = getimplemented(queries("Programming_Tasks"))
showunimp(x) = (println("\nUnimplemented in $x:"); for t in setdiff(alltasks,
getimplemented(queries(x))) println(t) end)
Unimplemented in Julia:
Active Directory/Connect
Active Directory/Search for a user
AVL tree
Catmull–Clark subdivision surface
Colour pinstripe/Printer
Create a file on magnetic tape
Joystick position
Machine code
OLE Automation
Pattern matching
Play recorded sounds
Rosetta Code/Find unimplemented tasks
Simulate input/Keyboard
Speech synthesis
Suffixation of decimal numbers
Superpermutation minimisation
Sutherland-Hodgman polygon clipping
Use another language to call a function
Yahoo! search interface

Unimplemented in C++:
15 puzzle solver
Abbreviations, automatic
Abbreviations, easy
Abbreviations, simple
Add a variable to a class instance at runtime
Balanced ternary
Brace expansion
Break OO privacy
Calendar - for "REAL" programmers
Call a foreign-language function
Call an object method
Casting out nines
Check Machin-like formulas
Church Numerals
Colour pinstripe/Printer
Commatizing numbers
Constrained genericity
Cuban primes
Define a primitive data type
Dynamic variable names
Eban numbers
Egyptian fractions
Factorial base numbers indexing permutations of a collection
First-class functions/Use numbers analogously
Fixed length records
Four is magic
Four is the number of letters in the ...
Hash join
History variables
Hunt The Wumpus
Idiomatically determine all the characters that can be used for symbols
Idiomatically determine all the lowercase and uppercase letters
Imaginary base numbers
Index finite lists of positive integers
Interactive programming
Joystick position
Knuth's power tree
Law of cosines - triples
Lucky and even lucky numbers
Lychrel numbers
Mayan numerals
Mind boggling card trick
Nested templated data
Nonogram solver
Object serialization
OLE Automation
OpenWebNet Password
Order disjoint list items
Partition an integer X into N primes
Pattern matching
Pig the dice game
Pig the dice game/Player
Play recorded sounds
Ramer-Douglas-Peucker line simplification
Range consolidation
Reflection/Get source
Reflection/List methods
Reflection/List properties
Respond to an unknown method call
Rosetta Code/Count examples
Rosetta Code/Find bare lang tags
Rosetta Code/Find unimplemented tasks
Rosetta Code/Fix code tags
Runtime evaluation
Runtime evaluation/In an environment
Safe primes and unsafe primes
Send an unknown method call
Solve a Holy Knight's tour
Solve a Hopido puzzle
Solve a Numbrix puzzle
Solve the no connection puzzle
Sort a list of object identifiers
Spelling of ordinal numbers
Strong and weak primes
Suffixation of decimal numbers
Sum and Product Puzzle
Topic variable
Twelve statements
URL parser
Video display modes
Word search
World Cup group stage
Yahoo! search interface
Zeckendorf arithmetic


Works with: Lua version 5.1 - 5.3
Library: lua-requests
local requests = require('requests')
local lang = arg[1]
local function merge_tables(existing, from_req)
local result = existing
for _, v in ipairs(from_req) do
result[v.title] = true
return result
local function get_task_list(category)
local url = ''
local query = {
action = 'query',
list = 'categorymembers',
cmtitle = string.format('Category:%s', category),
cmlimit = 500,
cmtype = 'page',
format = 'json'
local categories = {}
while true do
local resp = assert(requests.get({ url, params = query }).json())
categories = merge_tables(categories, resp.query.categorymembers)
if resp.continue then
query.cmcontinue = resp.continue.cmcontinue
return categories
local function get_open_tasks(lang)
if not lang then error('Language missing!') end
local all_tasks = get_task_list('Programming_Tasks')
local lang_tasks = get_task_list(lang)
local task_list = {}
for t, _ in pairs(all_tasks) do
if not lang_tasks[t] then
table.insert(task_list, t)
return task_list
local open_tasks = get_open_tasks(lang)
io.write(string.format('%s has %d unimplemented programming tasks: \n', lang, #open_tasks))
for _, t in ipairs(open_tasks) do
io.write(string.format('  %s\n', t))
Python has 24 unimplemented programming tasks:
  15 puzzle solver
  Bitmap/PPM conversion through a pipe
  Bitmap/Read an image through a pipe


#Example with the Maple Language
lan := "Maple":
x := URL:-Get(cat("", StringTools:-SubstituteAll(lan, " ", "_")), output = content):
x := StringTools:-StringSplit(x, "<h2><span class=\"mw-headline\" id=\"Not_implemented\">Not implemented</span>")[2]:
x := StringTools:-StringSplit(x, "<span class=\"mw-headline\" id=\"Draft_tasks_without_implementation\">Draft tasks without implementation</span>")[1]:
x := StringTools:-StringSplit(x,"<li><a href=\"/wiki/")[2..]:
for problem in x do
printf("%s\n", StringTools:-SubstituteAll(StringTools:-Decode(StringTools:-StringSplit(problem, "\" title=")[1], 'percent'), "_", " "));
end do:
#10:09 AM 10/05/2018
15 Puzzle Game
15 puzzle solver
24 game/Solve
4-rings or 4-squares puzzle
9 billion names of God the integer
AVL tree
Xiaolin Wu's line algorithm
Yahoo! search interface
Yin and yang
Zebra puzzle
Zeckendorf arithmetic
Zeckendorf number representation
Zhang-Suen thinning algorithm
Zig-zag matrix


Two implementations are considered, the first will use the API to get all the programming tasks, then the ones implemented for a certain language, and take the difference. The other will use the Tasks not implemented page and strip the html.

ImportAll[lang_String] :=
Module[{data, continue, cmcontinue, extra, xml, next},
data = {};
continue = True;
cmcontinue = "";
extra = If[cmcontinue =!= "", "&cmcontinue=" <> cmcontinue, ""];
xml = Import["" <> lang <> "&cmlimit=500&format=xml" <> extra, "XML"];
AppendTo[data, Cases[xml, XMLElement["cm", _, {}], \[Infinity]]];
next = Flatten[Cases[xml, {"cmcontinue" -> _}, \[Infinity]]];
If[Length[next] > 0,
next = First[next];
cmcontinue = "cmcontinue" /. next;
continue = False;
Cases[Flatten[data], HoldPattern["title" -> x_] :> x, \[Infinity]]
Complement[ImportAll["Programming_Tasks"], ImportAll["Mathematica"]]

which outputs a list of items not implemented:

{Abstract type,Active Directory/Connect,Active Directory/Search for a user,Address of a variable,<<139>>,Write to Windows event log,Xiaolin Wu's line algorithm,Zeckendorf arithmetic}

Another method is by getting the Tasks not implemented page:

url = "";
html = Import[url, "XMLObject"];
pos = Position[html, XMLElement["div", {"class" -> "mw-content-ltr", "dir" -> "ltr", "lang" -> "en"}, ___]];
pos = First[pos];
data = Extract[html, pos];
pos = Position[data, XMLElement["li", {}, {XMLElement["a", {"shape" -> "rect", "href" -> _, "title" -> x_}, {x_}]}]];
data = Extract[data, pos];
data = data[[All, -1, -1, 2]];
data = {"title", "href"} /. # & /@ %;
data[[All, 2]] = "" <> # & /@ data[[All, 2]];
newb = data[[All, 1]];
data = Hyperlink @@@ data;
data // Column
Append a record to the end of a text file
Arithmetic-geometric mean/Calculate Pi
Atomic updates
Bitcoin/address validation
Bitmap/PPM conversion through a pipe
Bitmap/Read an image through a pipe


import httpclient, strutils, xmldom, xmldomparser, cgi, os
proc findrc(category: string): seq[string] =
name = "$#&cmlimit=500&format=xml" % encodeUrl(category)
cmcontinue = @[""]
titles = newSeq[string]()
while true:
var x = getContent(name&cmcontinue[0]).loadXML()
for i in x.getElementsByTagName("cm"):
titles.add PElement(i).getAttribute("title")
cmcontinue = @[]
for i in x.getElementsByTagName("categorymembers"):
let u = PElement(i).getAttribute("cmcontinue")
if u != nil: cmcontinue.add encodeUrl(u)
if cmcontinue.len > 0:
cmcontinue[0] = "&cmcontinue=" & cmcontinue[0]
return titles
proc chooselang(): string =
if paramCount() < 1:
return "Nim"
return paramStr(1)
let alltasks = findrc("Programming_Tasks")
let lang = chooselang().findrc()
for i in alltasks:
if i notin lang:
echo $i


./unimplementedtasks Nim
24 game
24 game/Solve
9 billion names of God the integer
Abstract type
Active Directory/Connect
Active Directory/Search for a user
Active object
Add a variable to a class instance at runtime
AKS test for primes


Library: OzHttpClient

By parsing XML and using an XPath-like mechanism:

[HTTPClient] = {Link ['x-ozlib://mesaros/net/HTTPClient.ozf']}
[XMLParser] = {Link ['x-oz://system/xml/Parser.ozf']}
fun {FindUnimplementedTasks Language}
AllTasks = {FindCategory "Programming Tasks"}
LangTasks = {FindCategory Language}
{ListDiff AllTasks LangTasks}
fun {FindCategory Cat}
CatUrl = ""
#"&cmtitle=Category:"#{PercentEncode Cat}
fun {Loop CMContinue}
[_ Doc] = {Parse {GetPage CatUrl#CMContinue}}
Titles = {XPath Doc
[api query categorymembers cm {Attribute title}]}
case {XPath Doc
[api 'query-continue' categorymembers {Attribute cmcontinue}]}
of nil then Titles
[] [NewCMContinueAtom] then
NewCMContinue = {PercentEncode {Atom.toString NewCMContinueAtom}}
{Append Titles
{Loop "&cmcontinue="#NewCMContinue}}
{Loop nil}
%% XPath emulation
fun {XPath Doc Path}
P|Pr = Path
in = P %% assert
{FoldL Pr XPathStep [Doc]}
Nothing = {NewName}
fun {NotNothing X} X \= Nothing end
fun {XPathStep Elements P}
if { P} then
{FilteredChildren Elements P}
elseif { P} then
{Filter {Map Elements P} NotNothing}
%% A flat list of all Type-children of all Elements.
fun {FilteredChildren Elements Type}
{Map Elements
fun {$ E}
{Filter E.children
fun {$ X}
case X of element(name:!Type ...) then true
else false
fun {Attribute Attr}
fun {$ Element}
case {Filter Element.attributes fun {$ A} == Attr end}
of [A] then A.value
else Nothing
%% GetPage
Client = {New HTTPClient.urlGET init(inPrms(toFile:false toStrm:true) _)}
fun {GetPage RawUrl}
Url = {VirtualString.toString RawUrl}
{Client getService(Url ?OutParams ?_)}
fun {PercentEncode Xs}
case Xs of nil then nil
[] X|Xr then
if {Char.isDigit X} orelse {Member X [&- &_ &. &~]}
orelse X >= &a andthen X =< &z
orelse X >= &z andthen X =< &Z then
X|{PercentEncode Xr}
{Append &%|{ToHex2 X} {PercentEncode Xr}}
fun {ToHex2 X}
[{ToHex1 X div 16} {ToHex1 X mod 16}]
fun {ToHex1 X}
if X >= 0 andthen X =< 9 then &0 + X
elseif X >= 10 andthen X =< 15 then &A + X - 10
%% Parse
Parser = {New XMLParser.parser init}
fun {Parse Xs} {Parser parseVS(Xs $)} end
fun {ListDiff Xs Ys}
{FoldL Ys List.subtract Xs}
%% show tasks not implemented in Oz
{ForAll {FindUnimplementedTasks "Oz"} System.showInfo}


Using JSON (not parsed, just Regex.)

use LWP::Simple 'get';
my $fmt = '';
my $lang = shift
or die "No language given.\n";
sub urlencode
{join '', map {sprintf '%%%02x', ord} split //, shift}
sub tasks
{my $category = urlencode shift;
my @tasks;
my $json = get sprintf $fmt, $category;
for (;;)
{push @tasks, $json =~ /"title":"(.+?)"}/g;
$json =~ /"cmcontinue":"(.+?)"}/ or last;
$json = get sprintf $fmt . '&cmcontinue=%s',
$category, urlencode $1;}
return @tasks;}
my @all = tasks 'Programming_Tasks';
my %lang = map {$_, 1} tasks $lang
or die "No such category.\n";
$lang{$_} or print "$_\n"
foreach @all;

See also: User:ImplSearchBot/Code

Perl 6[edit]

Works with: Rakudo version 2018.04.1
use HTTP::UserAgent;
use URI::Escape;
use JSON::Fast;
use Sort::Naturally;
unit sub MAIN( Str :$lang = 'Perl_6' );
my $client =;
my $url = '';
my @total;
my @impl;
@total.append: .&get-cat for 'Programming_Tasks', 'Draft_Programming_Tasks';
@impl = get-cat $lang;
say "Unimplemented tasks in $lang:";
.say for (@total (-) @impl).keys.sort: *.&naturally;
sub get-cat ($category) {
flat mediawiki-query(
$url, 'pages',
).map({ .<title> });
sub mediawiki-query ($site, $type, *%query) {
my $url = "$site/api.php?" ~ uri-query-string(
:action<query>, :format<json>, :formatversion<2>, |%query);
my $continue = '';
gather loop {
my $response = $client.get("$url&$continue");
my $data = from-json($response.content);
take $_ for $data.<query>.{$type}.values;
$continue = uri-query-string |($data.<query-continue>{*}».hash.hash or last);
sub uri-query-string (*%fields) {{ "{.key}={uri-escape .value}" }).join("&") }


(load "@lib/http.l" "@lib/xm.l")
(de rosettaCategory (Cat)
(let (Cont NIL Xml)
(client "" 80
Cont )
(while (line))
(setq Xml (and (xml?) (xml))) )
(NIL Xml)
(for M (body Xml 'query 'categorymembers)
(link (attr M 'title)) )
(NIL (attr Xml 'query-continue' categorymembers 'cmcontinue))
(setq Cont (pack "&cmcontinue=" @)) ) ) ) )
(de unimplemented (Task)
(rosettaCategory "Programming_Tasks")
(rosettaCategory Task) ) )


I don't think this script follows the spirit of the task, but it works.

function Find-UnimplementedTask
$url = "$Language"
$web = Invoke-WebRequest $url
$unimplemented = 1
[string[]](($web.AllElements |
Where-Object {$_.class -eq "mw-content-ltr"})[$unimplemented].outerText -split "`r`n" |
Select-String -Pattern "[^0-9A-Z]$" -CaseSensitive)
$tasks = Find-UnimplementedTask -Language PowerShell
Write-Host "`nTotal unimplemented Tasks: $($tasks.Count)"
15 Puzzle Game
24 game/Solve
4-rings or 4-squares puzzle
9 billion names of God the integer
AKS test for primes 
Xiaolin Wu's line algorithm
Yahoo! search interface 
Yin and yang
Zebra puzzle 
Zeckendorf arithmetic 
Zhang-Suen thinning algorithm

Total unimplemented Tasks: 388


Library: mwclient

Given the name of a language on Rosetta Code,
finds all tasks which are not implemented in that language.

from operator import attrgetter
from typing import Iterator
import mwclient
URL = ''
API_PATH = '/mw/'
def unimplemented_tasks(language: str,
url: str,
api_path: str) -> Iterator[str]:
"""Yields all unimplemented tasks for a specified language"""
site = mwclient.Site(url, path=api_path)
all_tasks = site.categories['Programming Tasks']
language_tasks = site.categories[language]
name = attrgetter('name')
all_tasks_names = map(name, all_tasks)
language_tasks_names = set(map(name, language_tasks))
for task in all_tasks_names:
if task not in language_tasks_names:
yield task
if __name__ == '__main__':
tasks = unimplemented_tasks('Python', url=URL, api_path=API_PATH)
print(*tasks, sep='\n')

Library: Requests

Given the name of a language on Rosetta Code,
finds all tasks which are not implemented in that language.

from functools import partial
from operator import itemgetter
from typing import (Dict,
import requests
URL = ''
REQUEST_PARAMETERS = dict(action='query',
def unimplemented_tasks(language: str,
url: str,
request_params: Dict[str, Union[str, int, bool]]
) -> Iterator[str]:
"""Yields all unimplemented tasks for a specified language"""
with requests.Session() as session:
tasks = partial(tasks_titles,
all_tasks = tasks(cmtitle='Category:Programming_Tasks')
language_tasks = set(tasks(cmtitle=f'Category:{language}'))
for task in all_tasks:
if task not in language_tasks:
yield task
def tasks_titles(*,
session: requests.Session,
url: str,
**params: Union[str, int, bool]) -> Iterator[str]:
"""Yields tasks names for a specified category"""
while True:
request = session.get(url, params=params)
data = request.json()
yield from map(itemgetter('title'), data['query']['categorymembers'])
query_continue = data.get('query-continue')
if query_continue is None:
if __name__ == '__main__':
tasks = unimplemented_tasks('Python',
print(*tasks, sep='\n')

Library: urllib

import xml.dom.minidom
import urllib, sys
def findrc(category):
name = "" % urllib.quote(category)
cmcontinue, titles = '', []
while True:
u = urllib.urlopen(name + cmcontinue)
xmldata =
x = xml.dom.minidom.parseString(xmldata)
titles += [i.getAttribute("title") for i in x.getElementsByTagName("cm")]
cmcontinue = filter( None,
for i in x.getElementsByTagName("categorymembers")) )
if cmcontinue:
cmcontinue = '&cmcontinue=' + cmcontinue[0]
return titles
alltasks = findrc("Programming_Tasks")
lang = findrc(sys.argv[1])
for i in [i for i in alltasks if i not in lang]:
print i


Library: XML (R)
find.unimplemented.tasks <- function(lang="R"){
PT <- xmlInternalTreeParse( paste("",sep="") )
PT.nodes <- getNodeSet(PT,"//cm")
PT.titles = as.character( sapply(PT.nodes, xmlGetAttr, "title") )
language <- xmlInternalTreeParse( paste("",
lang, "&cmlimit=500&format=xml",sep="") )
lang.nodes <- getNodeSet(language,"//cm")
lang.titles = as.character( sapply(lang.nodes, xmlGetAttr, "title") )
unimplemented <- setdiff(PT.titles, lang.titles)
# Usage
langs <- c("R","python","perl")
sapply(langs, find.unimplemented.tasks) # fetching data for multiple languages


#lang racket
(require net/url net/uri-codec json (only-in racket/dict [dict-ref ref]))
(define (RC-get verb params)
((compose1 get-pure-port string->url format)
"" verb (alist->form-urlencoded params)))
(define (get-category catname)
(let loop ([c #f])
(define t
((compose1 read-json RC-get) 'api
`([action . "query"] [format . "json"]
[list . "categorymembers"] [cmtitle . ,(format "Category:~a" catname)]
[cmcontinue . ,(and c (ref c 'cmcontinue))] [cmlimit . "500"])))
(define (c-m key) (ref (ref t key '()) 'categorymembers #f))
(append (for/list ([page (c-m 'query)]) (ref page 'title))
(cond [(c-m 'query-continue) => loop] [else '()]))))
;; The above is the required "library" code, same as the "Rosetta
;; Code/Count" entry
(define (show-unimplemented lang)
(for-each displayln (remove* (get-category lang)
(get-category 'Programming_Tasks))))
(show-unimplemented 'Racket) ; see all of the Racket entries


# Project: Rosetta Code/Find unimplemented tasks
load "stdlib.ring"
ros= download("")
lang = "Ring"
pos = 1
num = 0
totalros = 0
rosname = ""
rostitle = ""
see "Tasks not implemented in " + lang + " language:" + nl
for n = 1 to len(ros)
nr = searchstring(ros,'<li><a href="/wiki/',pos)
if nr = 0
pos = nr + 1
nr = searchname(nr)
nr = searchtitle(nr)
see nl
see "Total: " + totalros + " examples." + nl
func searchstring(str,substr,n)
nr = substr(newstr, substr)
if nr = 0
return 0
return n + nr -1
func searchname(sn)
nr2 = searchstring(ros,'">',sn)
nr3 = searchstring(ros,"</a></li>",sn)
rosname = substr(ros,nr2+2,nr3-nr2-2)
return sn
func searchtitle(sn)
st = searchstring(ros,"title=",sn)
rostitle = substr(ros,sn+19,st-sn-21)
rostitle = "" + rostitle
rostitle = download(rostitle)
s = substr(rostitle,lang)
if s = 0
num = num + 1
totalros = totalros + 1
see "" + num + ". " + rosname + nl
return sn
func count(cstring,dstring)
sum = 0
while substr(cstring,dstring) > 0
sum = sum + 1
cstring = substr(cstring,substr(cstring,dstring)+len(string(sum)))
return sum


Tasks not implemented in Ring language:
1. 15 puzzle solver
2. 2048
3. 24 game/Solve
4. 9 billion names of God the integer
5. Abstract type
6. Active Directory/Search for a user
7. Address of a variable
8. AKS test for primes
9. Align columns
10. Amb
343. Xiaolin Wu's line algorithm
344. XML/DOM serialization
345. XML/Input
346. XML/Output
347. XML/XPath
348. Y combinator
349. Yahoo! search interface
350. Yin and yang
351. Zeckendorf arithmetic
352. Zhang-Suen thinning algorithm

Total: 352 examples.  


Finds tasks that are either not implemented or omitted. Sorts by task creation time.

Uses the RosettaCode module from Count programming examples#Ruby

require 'rosettacode'
require 'time'
module RosettaCode
def self.get_unimplemented(lang)
programming_tasks = []
category_members("Programming_Tasks") {|task| programming_tasks << task}
lang_tasks = []
category_members(lang) {|task| lang_tasks << task}
lang_tasks_omit = []
category_members("#{lang}/Omit") {|task| lang_tasks_omit << task}
[programming_tasks - lang_tasks, lang_tasks_omit]
def self.created_time(title)
url = get_api_url({
"action" => "query",
"titles" => title,
"format" => "xml",
"rvlimit" => 500,
"prop" => "revisions",
"rvprop" => "timestamp"
doc = open(url)
REXML::XPath.each(doc, "//rev").collect do |node|
Time.parse( node.attribute("timestamp").value )
lang = ARGV[0] || "Ruby"
unimplemented, omitted = RosettaCode.get_unimplemented(lang)
unimplemented.collect {|title| [title, RosettaCode.created_time(title)]} .
sort_by {|e| e[1]} .
each do |title, date|
puts "%s %6s %s" % [
omitted.include?(title) ? "[omit]" : "" ,

Output for Ruby

2010-04-05 11:08:07 -0500
2007-01-14        Table creation
2007-01-25 [omit] Pointers and references
2007-02-04        SQL-based authentication
2007-02-09        Metered concurrency
2007-02-27 [omit] Address of a variable
2007-02-27 [omit] Variable size/Set
2007-02-27        Variable size/Get
2007-06-08        OpenGL
2007-06-08        HTTPS/Authenticated
2007-11-06        Pattern matching
2007-11-08 [omit] Parametric polymorphism
2007-11-13        Special characters
2007-12-11        Arithmetic evaluation
2007-12-21 [omit] Proof
2007-12-24        Plot coordinate pairs
2007-12-24        Polynomial regression
2007-12-24        Compare sorting algorithms' performance
2008-03-27        Dragon curve
2008-03-28        Formal power series
2008-09-11        RCRPG
2008-11-02        Active object
2008-11-13        Window creation/X11
2008-12-05 [omit] Constrained genericity
2009-02-17        Rendezvous
2009-03-22        Arena storage pool
2009-05-23        Ray-casting algorithm
2009-05-26 [omit] Memory allocation
2009-05-26        Simulate input/Mouse
2009-05-27        Mouse position
2009-05-27        Keyboard macros
2009-05-27        Window management
2009-05-27        Color of a screen pixel
2009-06-01        HTTPS/Client-authenticated
2009-06-02        Simulate input/Keyboard
2009-06-08 [omit] Create an object at a given address
2009-06-10        Events
2009-06-10        Scope modifiers
2009-08-09        Verify distribution uniformity/Chi-squared test
2009-08-11        Call a function from a foreign language
2009-08-12        Safe addition
2009-12-05        Rate counter
2010-01-02        Loading Animated 3D Data
2010-01-06        Catmull–Clark subdivision surface
2010-01-21        Hough transform
2010-01-25        Compile-time calculation
2010-02-14        Knapsack problem/Bounded
2010-02-21        Deconvolution/1D
2010-02-23        Deconvolution/2D+
2010-02-24        Knapsack problem/Continuous
2010-03-23        Sutherland-Hodgman polygon clipping
2010-03-23        Find Common Directory Path

Run BASIC[edit]

Find tasks not implemented. Select Language from DropDown and click [GO] or [Exit].

WordWrap$ = "style='white-space: pre-wrap;white-space: -moz-pre-wrap;white-space: -pre-wrap;white-space: -o-pre-wrap;word-wrap: break-word'"
a$ = httpGet$("")
a$ = word$(a$,2,"mw-subcategories")
a$ = word$(a$,1,"</table>")
i = instr(a$,"/wiki/Category:")
html "<B> Select language from list<BR>"
html "<SELECT name='lang'>"
while i <> 0
j = instr(a$,""" title=""Category:",i)
lang$ = mid$(a$,i+15,j-i-15)
k = instr(a$,""">",j + 18)
langName$ = mid$(a$,j + 18,k-(j+18))
count = count + 1
html "<option value='";lang$;"'>";langName$;"</option>"
i = instr(a$,"/wiki/Category:",k)
html "</select>"
html "<p>Number of Languages:";count;"<BR> "
button #go,"GO", [go]
html " "
button #ex, "Exit", [exit]
lang$ = #request get$("lang")
h$ = "";lang$
a$ = httpGet$(h$)
a$ = word$(a$,3,"mw-content-ltr")
html "<table border=1><tr>"
i = instr(a$,"<a href=""/wiki/")
while i > 0
i = instr(a$,"title=""",i)
j = instr(a$,""">",i+7)
if c mod 4 = 0 then html "</tr><tr ";WordWrap$;">"
c = c + 1
html "<td>";mid$(a$,i+7,j-(i+7));"</td>"
i = instr(a$,"<a href=""/wiki/",i+7)
html "</tr></table>"
print "Total unImplemented Tasks:";c
24 game/SolveAbstract typeAccumulator factoryActive Directory/ConnectActive Directory/Search for a user
Arena storage poolArithmetic/RationalArithmetic evaluationAverage loop lengthAverages/Mean angle
Averages/Mean time of dayBitcoin/address validationBitmap/PPM conversion through a pipeBitmap/Read an image through a pipeBreak OO privacy
CRC-32CSV to HTML translationCalendarCalendar - for "real" programmersCall a function
Call an object methodCanny edge detectorCarmichael 3 strong pseudoprimes, or Miller Rabin's nemesisCatmull–Clark subdivision surfaceChat server
Check Machin-like formulasCholesky decompositionColour pinstripe/PrinterCompare sorting algorithms' performanceConstrained genericity
Continued fractionContinued fraction arithmetic/Continued fraction r2cf(Rational N)Continued fraction arithmetic/G(matrix NG, Contined Fraction N)Continued fraction arithmetic/G(matrix NG, Contined Fraction N1, Contined Fraction N2)Count the coins
Zebra puzzleZeckendorf number representation

Total unImplemented Tasks:177


Add to `build.sbt`

     libraryDependencies ++= Seq(
import com.softwaremill.sttp.json4s._
import com.softwaremill.sttp.quick._
implicit val serialization = org.json4s.native.Serialization
import org.json4s.DefaultFormats
implicit val formats = DefaultFormats
case class Task(pageid: Int, title: String)
case class Category(categorymembers: List[Task])
case class Query(query: Category)
List("Programming Tasks", "Scala")
.map { title =>
.header("User-Agent", mozillaUserAgent)
.map {
case Right(r) => r.query.categorymembers.toSet
case Left(s) => Set.empty[Task]
.foldRight(Set.empty[Task])((acc: Set[Task], ele: Set[Task]) => acc -- ele)


First, find all members of the Programming_Tasks category, then find all members of the $lang category. The difference is the list of unimplemented tasks.

Library: Tcllib (Package: json)
Library: Tcllib (Package: struct::set)
package require Tcl 8.5
package require http
package require json
package require struct::set
fconfigure stdout -buffering none
# Initialize a cache of lookups
array set cache {}
proc log msg {
#puts -nonewline $msg
proc get_tasks {category} {
global cache
if {[info exists cache($category)]} {
return $cache($category)
set base_url
set query {
action query
list categorymembers
cmtitle Category:%s
format json
cmlimit 500
set query [list {*}$query]; # remove excess whitespace
set this_query [dict create {*}[split [format $query $category]]]
set tasks [list]
while {1} {
set url [join [list $base_url [http::formatQuery {*}$this_query]] ?]
while 1 {
set response [http::geturl $url]
# Process redirects
if {[http::ncode $response] == 301} {
set newurl [dict get [http::meta $response] Location]
if {[string match http://* $newurl]} {
set url $newurl
} else {
set url [regexp -inline {http://[^/]+} $url]
append url $newurl
# Check for oopsies!
if {
[set s [http::status $response]] ne "ok"
|| [http::ncode $response] != 200
} then {
error "Oops: url=$url\nstatus=$s\nhttp code=[http::code $response]"
# Get the data out of the message
set data [json::json2dict [http::data $response]]
http::cleanup $response
# add tasks to list
foreach task [dict get $data query categorymembers] {
lappend tasks [dict get [dict create {*}$task] title]
if {[catch {
dict get $data query-continue categorymembers cmcontinue
} continue_task]} then {
# no more continuations, we're done
dict set this_query cmcontinue $continue_task
return [set cache($category) $tasks]
proc get_unimplemented {lang} {
set tasks [get_tasks Programming_Tasks]
set collected [get_tasks Collection_Members]
set doneTasks [get_tasks $lang]
set omittedTasks [get_tasks $lang/Omit]
# Map generic collection task categories to specific ones
set tasks [regsub -all {Category:(\S+)} $tasks "\\1/$lang"]
set collectOfLang [struct::set intersect $collected $doneTasks]
set ignorable [struct::set union $doneTasks $omittedTasks $collectOfLang]
set unimplemented [struct::set difference $tasks $ignorable]
puts "\n$lang has [llength $unimplemented] unimplemented programming tasks:"
if {[llength $unimplemented]} {
puts " [join [lsort $unimplemented] "\n "]"
catch {console show}
catch {wm withdraw .}
foreach lang {Perl Python Ruby Tcl} {
get_unimplemented $lang


Uses shared libraries YAJL and cURL.

var [const] YAJL=Import("zklYAJL")[0], CURL=Import("zklCurl");
fcn getTasks(language){
continueValue,tasks:="",Data(0,String); // "nm\0nm\0...."
page=page[0].del(0,page[1]); // get rid of HTML header
continueValue=json.find("continue") //continue:-||,cmcontinue:page|954|19)
allTasks:=getTasks.future("Programming_Tasks"); // thread
langTasks:=Dictionary(); tasks.pump(Void,langTasks.add.fp1(Void));
unimplementedTasks:=allTasks.filter('wrap(nm){ (not langTasks.holds(nm)) });
println("Found %d unimplemented tasks for %s:"
Found 166 unimplemented tasks for zkl:
15 Puzzle Game
Address of a variable
Animate a pendulum
Zeckendorf arithmetic
Zhang-Suen thinning algorithm