The Erlang logger application introduced in OTP 21 is extremely flexible, but the default settings are not the most practical for development purposes: The default log level is notice, meaning that info and debug messages will not be printed. Log messages with a domain other than [otp] will not be printed. Each...

I use Dialyzer a lot, and it has always been useful to expose various errors in my Erlang code. Unfortunately, I recently discovered an unexpected behaviour: by default, Dialyzer ignores unknown types. It is very surprising and suddently makes me doubt any piece of Erlang code I ever wrote. As it turns out, there is...

The CLHS, or Common Lisp HyperSpec, is one of the most important resource for any Common Lisp developer. It is derived from the official Common Lisp standard, and contains documentation for every aspect of the language. While it is currently made available online by LispWorks, it can be useful to be able to access...

The usual way to develop programs in Common Lisp is to use SLIME in Emacs, which starts an implementation and provides a REPL. When a program needs to be running in production, one can either execute it from source or compile it to an executable core, for example with sb-ext:save-lisp-and-die in SBCL. While...

While the erl application is really useful to tinker with Erlang modules, the lack of a persistent history has always been annoying. I recently discovered via Adopting Erlang that the history can be made persistent since Erlang 20 with specific flags, which can be added to the ERL_AFLAGS environment variable to have...

I am used to read RFC documents in Emacs by opening them as simple text files. But I was always annoyed by the impossibility to follow references to other documents. Additionally, searching for the right RFC usually involve going back to the web browser and Google while I would prefer staying in Emacs. Since I enjoy...

I have been learning a lot about Erlang recently, and I stumbled upon a strange behaviour: printing strings containing non-ascii characters, e.g. "μs", using io:format and the ~ts control sequence behaves differently depending on the way the program is run: In rebar3 shell, rebar3 run, or a release running with a...

I have been using Emacs for some time, and ido has always been my favourite way to switch buffers. But recently I discovered and started using Helm, a package based on incremental completion which can provide lots of interesting features. One of them being buffer switching. The simplest way to use Helm to switch...