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POHow to debug Erlang code?
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copied!<p>I have some Ruby and Java background and I'm accustomed to having exact numbers of lines in the error logs. </p> <p>So, if there is an error in the compiled code, I will see the number of line which caused the exception in the console output.</p> <p>Like in this Ruby example:</p> <pre><code>my_ruby_code.rb:13:in `/': divided by 0 (ZeroDivisionError) from my_ruby_code.rb:13 </code></pre> <p>It's simple and fast - I just go to the line number 13 and fix the error.</p> <p>On the contrary, Erlang just says something like:</p> <pre><code>** exception error: no match of right hand side value [xxxx] in function my_module:my_fun/1 in call from my_module:other_fun/2 </code></pre> <p>There are no line numbers to look at. </p> <p>And if I have two lines like</p> <pre><code>X = Param1, Y = Param2, </code></pre> <p>in 'my_fun', how can understand in which line the problem lies? </p> <p>Additionally, I have tried to switch to Emacs+Elang-mode from Vim, but the only bonus I've got so far is the ability to cycle through compilation errors inside Emacs (C-k `).</p> <p>So, the process of writing code and seeking for simple logical errors like 'no match of right hand side' seems to be a bit cumbersome.</p> <p>I have tried to add a lot of "io:format" lines in the code, but it is additional work which takes time.</p> <p>I have also tried to use <a href="http://bc.tech.coop/blog/070528.html" rel="noreferrer">distel</a>, but it requires 10 steps to just open a debugger once.</p> <p>Questions:</p> <ol> <li>What is the most straight and simple way to debug Erlang code?</li> <li>Does Emacs' erlang-mode has something superior in terms of Erlang development comparing to Vim?</li> <li>What development 'write-compile-debug' cycle do you prefer? Do you leave Emacs to compile and run the code in the terminal? How do you search for errors in your Erlang code? </li> </ol>

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