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<spanid="cb1-2"><ahref="#cb1-2" aria-hidden="true" tabindex="-1"></a> (<spanclass="va">#'clojure.core/print-object</span> x w))</span></code><buttontitle="Copy to Clipboard" class="code-copy-button"><iclass="bi"></i></button></pre></div>
<p>The syntax is <code>#object[CLASS-NAME HASH toString())]</code> and as you can see, the toString of an Object is <code>CLASS-NAME@HASH</code>. For most objects this becomes quite a long string.</p>
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<divclass="sourceCode" id="cb5"><preclass="sourceCode clojure code-with-copy"><codeclass="sourceCode clojure"><spanid="cb5-1"><ahref="#cb5-1" aria-hidden="true" tabindex="-1"></a>(async/chan)</span></code><buttontitle="Copy to Clipboard" class="code-copy-button"><iclass="bi"></i></button></pre></div>
<divclass="sourceCode" id="cb8"><preclass="sourceCode clojure code-with-copy"><codeclass="sourceCode clojure"><spanid="cb8-1"><ahref="#cb8-1" aria-hidden="true" tabindex="-1"></a>#object[clojure.print_object.remove_extraneous$eval22450$fn__22451<spanclass="bn">0x6bb35b0e</span><spanclass="st">"clojure.print_object.remove_extraneous$eval22450$fn__22451@6bb35b0e"</span>]</span></code><buttontitle="Copy to Clipboard" class="code-copy-button"><iclass="bi"></i></button></pre></div>
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<divclass="sourceCode" id="cb8"><preclass="sourceCode clojure code-with-copy"><codeclass="sourceCode clojure"><spanid="cb8-1"><ahref="#cb8-1" aria-hidden="true" tabindex="-1"></a>#object[clojure.print_object.remove_extraneous$eval22473$fn__22474<spanclass="bn">0x44bff65c</span><spanclass="st">"clojure.print_object.remove_extraneous$eval22473$fn__22474@44bff65c"</span>]</span></code><buttontitle="Copy to Clipboard" class="code-copy-button"><iclass="bi"></i></button></pre></div>
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<p>It’s quite easy to miss the fact that it is a function as we are looking for a tiny little <code>fn</code> in a sea of text. If, like me, you are fond of the <ahref="../../code_interview/beating/with_stupid_stuff/z_combinator_gambit.html">odd lambda calculus excursion</a>, things get even more hectic.</p>
<divclass="sourceCode" id="cb10"><preclass="sourceCode clojure code-with-copy"><codeclass="sourceCode clojure"><spanid="cb10-1"><ahref="#cb10-1" aria-hidden="true" tabindex="-1"></a>#object[clojure.print_object.remove_extraneous$eval22454$fn__22455$fn__22456<spanclass="bn">0x6a544178</span><spanclass="st">"clojure.print_object.remove_extraneous$eval22454$fn__22455$fn__22456@6a544178"</span>]</span></code><buttontitle="Copy to Clipboard" class="code-copy-button"><iclass="bi"></i></button></pre></div>
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<divclass="sourceCode" id="cb10"><preclass="sourceCode clojure code-with-copy"><codeclass="sourceCode clojure"><spanid="cb10-1"><ahref="#cb10-1" aria-hidden="true" tabindex="-1"></a>#object[clojure.print_object.remove_extraneous$eval22477$fn__22478$fn__22479<spanclass="bn">0x16165af2</span><spanclass="st">"clojure.print_object.remove_extraneous$eval22477$fn__22478$fn__22479@16165af2"</span>]</span></code><buttontitle="Copy to Clipboard" class="code-copy-button"><iclass="bi"></i></button></pre></div>
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<p>Yikes! what an eyesore. This is not an academic issue specific to lambda calculus. Any function created from inside a function is helpfully identifiable through the <code>fn$fn</code> nesting. We create these quite regularly, and they are often printed in stack traces. I’m sure you have seen them when you map an inline function across a seq, and there is a bug in the anonymous function.</p>
<spanid="cb13-4"><ahref="#cb13-4" aria-hidden="true" tabindex="-1"></a> [clojure.core$mapv$fn__8565 invoke <spanclass="st">"core.clj"</span><spanclass="dv">7059</span>]]</span></code><buttontitle="Copy to Clipboard" class="code-copy-button"><iclass="bi"></i></button></pre></div>
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<p>See that part <code>caesar_cipher$add2</code>? That is <strong>very</strong> useful information. It tells us that the exception was inside <code>add2</code>, which is inside <code>caesar-cipher</code>. The stack trace doesn’t print functions as objects, but it illustrates that the thing that we care about is that they are a function, what their name is, and whether they were created from inside another function.</p>
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