A coder is someone who writes code, naturally. :)  "code" is something intended to be interpreted or executed by a computer or a computer program. 

I think everyone agrees that anyone is welcome at code4lib. 

However, many want to keep code4lib conference presentations and community focused on technical matters and matters of interest to coders. 

These things are not neccesarily contradictorily.  
From: Code for Libraries [[log in to unmask]] on behalf of Mark A. Matienzo [[log in to unmask]]
Sent: Wednesday, November 28, 2012 10:02 PM
To: [log in to unmask]
Subject: [CODE4LIB] What is a "coder"?

Some discussion (both on-list and otherwise) has referred to "coders,"
and some discussion as such has raised the question whether
"non-coders" are welcome at code4lib.

What's a coder? I'm not trying to be difficult - I want to make
code4lib as inclusive as possible.

Mark A. Matienzo <[log in to unmask]>
Digital Archivist, Manuscripts and Archives, Yale University Library
Technical Architect, ArchivesSpace