<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">BTW, this question has apparently come up before (multiple times). The key google phrase is "Y combinator":<div><span class="Apple-tab-span" style="white-space:pre"> </span><a href="http://bc.tech.coop/blog/070611.html">http://bc.tech.coop/blog/070611.html</a></div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Steven</div><div><br><div><div>On Oct 5, 2008, at 2:13 AM, Edwin Fine wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr">I'm assuming that you want to do this in the shell, otherwise it would be easier just to write the function in the usual way, e.g.<br><br>myfun() -><br> blah, blah,<br> myfun().<br><br>To create a fun that calls itself, you must realize that you are creating an unnamed function. When you write<br> <br>fun(X) -> X * 2 end.<br><br>this is compiled to a Fun data type, e.g. #Fun<erl_eval.6.13229925>.<br><br>Since the function does not have a name, it cannot refer to itself.<br><br>When you write FunVar = fun(X) -> X * 2 end, the function is bound to the variable FunVar. Because the binding takes place *after* the fun is created, the fun cannot refer to the variable FunVar within its definition.<br> <br>So how is it done? You have to pass the variable to the function so that it "knows" what to call:<br><br>FunVar =<br> fun(MySelf) -> <br> ...<br> MySelf().<br><br>Then when you call it, you call FunVar(FunVar). Looks strange but it works.<br> <br>Example: Writing a simple generate and fold function using only a fun() variable.<br><br><span style="font-family: courier new,monospace;">9> GenFold = </span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> fun(0, Acc, _) -><br> Acc;</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> (X, Acc, Fun) -><br> Fun(X - 1, [X|Acc], Fun)</span><br style="font-family: courier new,monospace;"> <span style="font-family: courier new,monospace;"> end.</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">#Fun<erl_eval.18.105910772></span><br style="font-family: courier new,monospace;"> <span style="font-family: courier new,monospace;">10> GenFold(10, [], GenFold). </span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">[1,2,3,4,5,6,7,8,9,10]</span><br style="font-family: courier new,monospace;"> <span style="font-family: courier new,monospace;">11> </span><br><br>Or a for loop:<br><br><span style="font-family: courier new,monospace;">22> For = <br> fun(Max, Max, ExecFun, _) -><br> ok;<br> (N, Max, ExecFun, Next) -><br> ExecFun(N),<br> Next(N + 1, Max, ExecFun, Next)<br> end. </span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">#Fun<erl_eval.4.105156089></span><br style="font-family: courier new,monospace;"> <span style="font-family: courier new,monospace;">23> For(0,10,fun(I) -> io:format("~B ", [I]) end, For). </span><br style="font-family: courier new,monospace;"> <span style="font-family: courier new,monospace;">0 1 2 3 4 5 6 7 8 9 ok</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">24> </span><br><br>Stuff like this is described in Joe Armstrong's Erlang book.<br> <br>Hope this helps.<br><br><div class="gmail_quote">On Sat, Oct 4, 2008 at 11:19 PM, deepblue_other <span dir="ltr"><<a href="mailto:cktgatb@gmail.com">cktgatb@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> <br> hello<br> I have this going on<br> <br> FunVar =<br> fun() -><br> ...<br> FunVar()<br> end.<br> <br> so the compiler is complaining that FunVar is unbound at the place where its<br> being used inside fun(); this makes sense, however Im wondering how to make<br> this into a recursive function since there's no name to reference the<br> function with.<br> <br> thanks<br> <font color="#888888">--<br> View this message in context: <a href="http://www.nabble.com/recursive-fun%28%29-tp19820386p19820386.html" target="_blank">http://www.nabble.com/recursive-fun%28%29-tp19820386p19820386.html</a><br> Sent from the Erlang Questions mailing list archive at Nabble.com.<br> <br> _______________________________________________<br> erlang-questions mailing list<br> <a href="mailto:erlang-questions@erlang.org">erlang-questions@erlang.org</a><br> <a href="http://www.erlang.org/mailman/listinfo/erlang-questions" target="_blank">http://www.erlang.org/mailman/listinfo/erlang-questions</a><br> <br> </font></blockquote></div><br></div> _______________________________________________<br>erlang-questions mailing list<br><a href="mailto:erlang-questions@erlang.org">erlang-questions@erlang.org</a><br>http://www.erlang.org/mailman/listinfo/erlang-questions</blockquote></div><br></div></body></html>