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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=ES link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi Diego,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I don’t know exactly if this could work for you but you can do complex patterns like this to take what you want<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Courier New";color:#1F497D'><span style='mso-list:Ignore'>1><span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Courier New";color:#1F497D'>ets:new(table, [named_table]),<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Courier New";color:#1F497D'><span style='mso-list:Ignore'>2><span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Courier New";color:#1F497D'>ets:insert(</span><tt><i><span lang=EN-US style='font-size:10.0pt'>"Peter", [{"children", ["Bob", "Paul"]}, {"father", ["Mike"]}]}</span></i></tt><span lang=EN-US style='font-size:10.0pt;font-family:"Courier New";color:#1F497D'>),<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Courier New";color:#1F497D'><span style='mso-list:Ignore'>3><span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Courier New";color:#1F497D'>ets:match(table, {"Peter", [{"children", '$1'},'_'] }).<o:p></o:p></span></p><p class=MsoListParagraph><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>[[["Bob","Paul"]]]<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you always match against the key, you do really faster.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Bests,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Ivan.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>De:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> erlang-questions-bounces@erlang.org [mailto:erlang-questions-bounces@erlang.org] <b>En nombre de </b>Diego Llarrull<br><b>Enviado el:</b> lunes, 04 de marzo de 2013 14:58<br><b>Para:</b> erlang-questions@erlang.org<br><b>Asunto:</b> [erlang-questions] Nested match specifications?<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>Hello everyone, <br><br>I would like to insert in an ETS table a tuple with the following type signature: <br><br><tt><i><span style='font-size:10.0pt'>{string(), [{string(), [string()]}]}</span></i></tt><br><br>As an example: <br><i><br></i><tt><i><span style='font-size:10.0pt'>{"Peter", [{"children", ["Bob", "Paul"]}, {"father", ["Mike"]}]}</span></i></tt><i><br><br></i><br>My question is the following: is it possible to solve, using match specifications, nested queries like "Retrieve the name of Peter's children" ?<br><br>That is, a query where I would need to <br><br>a) Fetch all ("the", since its a set) tuples of size 3 where "Peter" is located in the first position (doable with MS)<br>b) Let '$2' be the value in the second position of the tuple fetched in a). Then, fetch the value corresponding to the key "children" in '$2', if interpreted as a key-value list (i.e. lists:keyfind() should work on '$2'). <br><br>If I understood correctly, lists:keyfind can't be used inside a match specification because they only allow the BIFs described in <a href="http://www.erlang.org/doc/apps/erts/match_spec.html">http://www.erlang.org/doc/apps/erts/match_spec.html</a>. My question is: is there any low-level mechanism to operate on lists inside match specifications, or am I trying to push the boundaries of match specifications?<br><br>In case anyone wonders "Why not use Query Lists Comprehensions?" the answer is: "Because of performance issues: in our platform, we need to dynamically build QLCs based on the number of arguments that arrive, which forces us to build them as strings and then use qlc:string_to_handle() which is SLOW". <br><br>Any help of insight will be greatly appreciated. Thank you very much in advance. <br><br>Diego Llarrull<br><br> <o:p></o:p></p></div></body></html>