Programming Erlang, 2nd Edition

Debugging Techniques

Debugging Erlang is pretty easy. That might surprise you, but this is a consequence of having single-assignment variables. Since Erlang has no pointers and no mutable state (with the exception of ETS tables and process dictionaries), finding out where things have gone wrong is rarely a problem. Once we have observed that a variable has an incorrect value, it’s relatively easy to find out when and where this happened.

I find a debugger is a very helpful tool when I write C programs, because I can tell it to watch variables and tell me when their value changes. This is often important because memory in C can be changed indirectly, via pointers. It can be hard to know just where a change to some chunk of memory came from. ...