Erlang

rebar3 tree is a new command to allow the user to view what dependency pulled in each transitive dependency. This is especially useful with rebar3’s dependency resolution strategy of “first wins”. Thanks for pushing for this feature goes to Heinz N. Gies and inspiration comes from leiningen’s command lein deps :tree. For an example I’ve cloned chef-server and built oc_erchef under src/oc_erchef. It is unique because it has both a top level app oc_erchef under src/ as well as additional project apps under apps/. ...

Update January 22, 2016: The original post has been modified to reflect that the commands install and upgrade were moved from the unstable namespace to the local namespace. Also added is use of the environment variable $REBAR3_ERL_ARGS in the run script which allows the user to specify custom Erlang VM arguments like: REBAR3_ERL_ARGS="+A10" rebar3 shell. Rebar3 comes with a lot of new and improved features. I’ll be publishing posts here to highlight some of these features over the coming weeks. ...

Almost exactly a year ago I was looking to merge the many forks of Will Glozer’s Postgres client for use in a project at Heroku. Instead Semiocast released their client, I gave it a try and never looked back. (But note that David Welton, a braver person than me, is working on merging the forks of epgsql at this time). I found Semiocast’s client to be clean, stable and I liked the interface better. ...

UPDATE: I’m seeing that I did not make the point of this post clear. I am not saying Go is wrong or should change because it isn’t like Erlang. What I am attempting to show is the choices Go made that make it not an alternative to Erlang for backends where availability and low latency for high numbers of concurrent requests is a requirement. And notice I’m not writing this about a language like Julia. ...

There is a great new Emacs plugin from Eric Merritt that like FlyMake builds your code and highlights within Emacs any errors or warnings, but unlike FlyMake builds across the whole project. You can clone the mode from here projmake-mode After cloning the repo to your desired location add this bit to your dot emacs file, replacing <PATH> with the path to where you cloned the repo. [gist]3794732[/gist] This Emacs code also uses add-hook to set projmake-mode to start for erlang-mode is loaded. ...

Working with Erlang for writing RESTful interfaces JSON is the communication “language” of choice. For simplifying the process of JSON to a model the backend could work with efficiently I’ve created maru_models. This app decodes the JSON with jiffy and uses functions generated by a modified version of Ulf’s exprecs to create an Erlang record. The generated functions are created with type information from the record definition and when a property is set for the record through these functions it is first passed to the convert function of maru_model_types to do any necessary processing. ...

TLDR; Copy and paste the following into your elisp erlang-mode configuration to get flymake working with Rebar projects. Intro Its probably no great surprise to anyone that I dislike Rebar a lot. That said there are times when I have no choice but to use it. This is always either because a company I am contracting for uses it, or an open source project I am contributing to uses it. When I am forced to use it there are a few things I don’t want to give up. ...

Fred, of Learn You Some Erlang for Great Good, today posted on his blog about the problems around how rebar handles releases, Rebar Releases and Being Wrong. The problems he mentions and a few others are why, despite giving it a legitimate shot, I have found rebar unusable for my workflow to be efficient and stable while adhering to OTP standards at the same time. I suggest first reading his post, if you already use rebar, and then continuing on with the rest of this. ...

Why Cowboy and Batman.js There are a lot of Erlang web frameworks out there today. Not all are modeled after the MVC model (see Nitrogen), but I think all of them are addressing the problem the wrong way. I recently gave a presentation, slides here and the code for this example here, describing my perferred method for using Erlang for web development and why I think it is the best way to go. ...

I’ll have a complete walk of through using Cowboy and Batman.js to build the TodoMVC clone in a few days. For now I have the slides from my talk at the Chicago Erlang User Group: Chicago Erlang User Group April, 4th 2012 I couldn’t get iframe embedding to work with Wordpress… So if anyone knows what that is up with please comment.