math functions with clojure

Question

I download the clojure 1.2 and clojure-contrib-1.2.0.jar from the download site.

And I found the info about the math functions.

As is shown in the example, I tried to run the code.

(ns your-namespace
  (:require clojure.contrib.generic.math-functions))
(println (abs 10))

But, I got the following error, when I run as follows.

CLOJURE_JAR=/Users/smcho/bin/jar/clojure.jar:/Users/smcho/bin/jar/clojure-contrib-1.2.0.jar
java -cp $CLOJURE_JAR:$CLASSPATH clojure.main SOURCE.CLJ

Exception in thread "main" java.lang.Exception: Unable to resolve symbol: abs in this context (hello.clj:4)
    at clojure.lang.Compiler.analyze(Compiler.java:5205)
        ...
    at clojure.main.main(main.java:37)
Caused by: java.lang.Exception: Unable to resolve symbol: abs in this context
    at clojure.lang.Compiler.resolveIn(Compiler.java:5677)
    at clojure.lang.Compiler.resolve(Compiler.java:5621)
    at clojure.lang.Compiler.analyzeSymbol(Compiler.java:5584)
    at clojure.lang.Compiler.analyze(Compiler.java:5172)
    ... 25 more

What might be wrong?

Answer 1

Try :use instead of :require

(ns your-namespace
  (:use clojure.contrib.generic.math-functions))
(println (abs 10))
10
nil

Require makes the symbol (abs in this case) available, but you'd have to fully qualify it. Use imports the symbol into "your-namespace":

(ns your-namespace2
  (:require clojure.contrib.generic.math-functions))
(println (clojure.contrib.generic.math-functions/abs 10))
10
nil