I've started working on a chess game in Clojure, but am having trouble with my namespace. At the top of my file, I have
(ns chess.core
(:require clojure.contrib.str-utils2))
and also define several functions, including to-string, which turns the symbol for a game piece into a string. However, when I compile:
core.clj:21:8:
error: java.lang.Exception: Unable to resolve symbol: to-string in this context (core.clj:21)
I've done some experimenting, and discovered that I get an error the first time I call a function that I defined myself. I've also discovered that I usually don't get an error if I comment out the ns call. Sometimes it can be fixed by restarting the Swank server (and sometimes it can't). For a while I just had (ns chess.core), which threw the same error, so I commented it out and continued hacking. But now I need to upper-case something, so I need str-utils.
Speaking about str-utils, I use Leiningen, and have the following in project.clj under :dependencies:
[org.clojars.jhowarth/clojure-contrib "1.2.0-RC3"]]
; [clojure.contrib.str-utils2 "1.2.1"]]
The top one works, the bottom one doesn't.
So I feel like I'm just ignorant about how Clojure namespacing and libraries work, but at the same time everyone else seems to be using (ns foo.bar) successfully.
When compiling, the definitions are evaluated from top to bottom. If you refer to a function that is defined later in the file, you'll get that error. I'm thinking that by removing the ns at the top, you're actually referring to a function with the same name in another namespace (probably the default user ns).
If you can't move the function to above its first use, you can do a (declare to-string) at the top and define it later.
As for the str-utils2 package, it should already be in clojure-contrib 1.2X. Starting from 1.3 (which isn't finished), contrib will be split up. See http://groups.google.com/group/clojure/msg/c5cdfec990efb6f4