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I'm a Clojure and JVM beginner, and the build tools are a bit confusing to me, so forgive the stupidity I'm about to carry out. I don't actually know what a "classpath" is... I just want a Lisp with lots of libraries!

But I'm trying to do a write a simple little bit of text-mining code in Clojure, and I don't seem to be able to get things working.

There are two problems, and I think they're related, both probably to this classpath thing from javaland that none of the introductory Clojure books seem to explain.

I started the project with lein new and my project.clj has the following dependencies:

 :dependencies [[org.clojure/clojure "1.6.0"] 
                 [clj-fuzzy "0.1.8"]
                 [snowball-stemmer "0.1.0"]
                 [net.mikera/core.matrix "0.50.0"]])

and the relevant ns call from my core.clj is as follows:

(ns blabber.core 
  (:require 
    [clojure.string :refer [lower-case split]]
    [clojure.walk :refer [keywordize-keys]]))

My directory structure is the default setup leiningen uses for a new library.

First problem:

I gather from this prior SO that if things are set up right, I shouldn't need to call (load-file "src/blabber/core.clj") in the repl before calling (use 'blabber.core) in order to get at code I just wrote. (I'm firing up the lein repl from the src/blabber directory in bash). But when I fire up the repl, use fails unless I call load-file first. So does that mean my classpath is set up wrong somehow? And how does one fix such a thing?

Second problem:

Ok, so now I'm trying to actually use core.matrix. First line of my core.clj changed to:

(ns blabber.core 
  (:require 
    [clojure.string :refer [lower-case split]]
    [clojure.walk :refer [keywordize-keys]]
    [clojure.core.matrix :refer [dataset]]))

When I first started the repl with this project.clj but without the :require to core.matrix, leiningen happily fetched core.matrix: Retrieving net/mikera/core.matrix/0.50.0/core.matrix-0.50.0.jar from clojars

However, after including the :require to core.matrix in the actual code and starting up the repl again, at the repl I call (load-file "src/blabber/core.clj"), and get the following error:

CompilerException java.io.FileNotFoundException: Could not locate clojure/core/matrix__init.class or clojure/core/matrix.clj on classpath: , compiling:(/Users/pauliglot/github/blabber/src/blabber/core.clj:1:1)

I'm using Leiningen 2.5.1 on Java 1.8.0_45. And I'm just following the getting started guide for core.matrix.

So what happened? Why can't the JVM find any of my stuff? Save me? Thanks!

If it helps, here's a dump of the output of lein classpath

/Users/pauliglot/github/blabber/test:/Users/pauliglot/github/blabber/src:/Users/pauliglot/github/blabber/dev-resources:/Users/pauliglot/github/blabber/resources:/Users/pauliglot/github/blabber/target/classes:/Users/pauliglot/.m2/repository/clj-fuzzy/clj-fuzzy/0.1.8/clj-fuzzy-0.1.8.jar:/Users/pauliglot/.m2/repository/snowball-stemmer/snowball-stemmer/0.1.0/snowball-stemmer-0.1.0.jar:/Users/pauliglot/.m2/repository/org/clojure/tools.macro/0.1.5/tools.macro-0.1.5.jar:/Users/pauliglot/.m2/repository/clojure-complete/clojure-complete/0.2.3/clojure-complete-0.2.3.jar:/Users/pauliglot/.m2/repository/org/clojure/google-closure-library-third-party/0.0-20140226-71326067/google-closure-library-third-party-0.0-20140226-71326067.jar:/Users/pauliglot/.m2/repository/com/google/protobuf/protobuf-java/2.4.1/protobuf-java-2.4.1.jar:/Users/pauliglot/.m2/repository/org/clojure/google-closure-library/0.0-20140226-71326067/google-closure-library-0.0-20140226-71326067.jar:/Users/pauliglot/.m2/repository/org/mozilla/rhino/1.7R4/rhino-1.7R4.jar:/Users/pauliglot/.m2/repository/org/json/json/20090211/json-20090211.jar:/Users/pauliglot/.m2/repository/net/mikera/core.matrix/0.50.0/core.matrix-0.50.0.jar:/Users/pauliglot/.m2/repository/com/google/javascript/closure-compiler/v20131014/closure-compiler-v20131014.jar:/Users/pauliglot/.m2/repository/com/google/code/findbugs/jsr305/1.3.9/jsr305-1.3.9.jar:/Users/pauliglot/.m2/repository/org/clojure/clojurescript/0.0-2202/clojurescript-0.0-2202.jar:/Users/pauliglot/.m2/repository/args4j/args4j/2.0.16/args4j-2.0.16.jar:/Users/pauliglot/.m2/repository/org/clojure/tools.nrepl/0.2.6/tools.nrepl-0.2.6.jar:/Users/pauliglot/.m2/repository/com/google/guava/guava/15.0/guava-15.0.jar:/Users/pauliglot/.m2/repository/org/clojure/clojure/1.6.0/clojure-1.6.0.jar:/Users/pauliglot/.m2/repository/org/clojure/tools.reader/0.8.3/tools.reader-0.8.3.jar:/Users/pauliglot/.m2/repository/org/clojure/data.json/0.2.3/data.json-0.2.3.jar

Edit Here's the directory tree: | blabber |-doc |-resources |-src |---blabber |-target |---classes |-----META-INF |-------maven |---------blabber |-----------blabber |---stale |-test

and all my code is in blabber/src/blabber/core.clj

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Paul Gowder
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    A classpath is a Java concept; Leiningen should set up the classpath correctly. What I suspect is that there's a mismatch between the directories, filenames, or namespace declarations. The file path should be `/src/blabber/core.clj`. It wasn't clear from what you wrote whether that's the case. Try running `lein deps` first, too, but you shouldn't need to do that. This and `lein repl` are usually run from the `` directory. You might need `:source-paths` or `:main` in project.clj, but I don't think so. – Mars Mar 17 '16 at 03:58
  • I'm pretty sure the file path is right. (blabber was the name passed to lein new... Im 95% sure. wonder if there's a log somewhere to make sure?). will try `lein deps` --- also editing to add the directory tree. – Paul Gowder Mar 17 '16 at 04:16
  • iiinteresting. After running `lein deps` and starting the repl from the project root (name passed to lein new) directory, the repl can find my code, but it still can't find core matrix. `(use 'blabber.core)` throws `CompilerException java.io.FileNotFoundException: Could not locate clojure/core/matrix__init.class or clojure/core/matrix.clj on classpath: , compiling:(blabber/core.clj:1:1)` – Paul Gowder Mar 17 '16 at 04:21
  • hmm. I'm starting to suspect that this is a glitch in the docs for core.matrix, because I just started up a dummy project, listed `[net.mikera/core.matrix "0.50.0"]` as a dependency, and tried to simply `(use 'clojure.core.matrix)` from the repl, and it threw the same error. Or maybe I'm being an idiot in some obvious way... – Paul Gowder Mar 17 '16 at 04:27
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    This should work. Works for me, e.g. with `(defproject blabber "0.1.0-SNAPSHOT" :dependencies [[org.clojure/clojure "1.8.0"] [net.mikera/core.matrix "0.50.0"]])`. (FWIW, I bet that half of all new Clojure programmers go through similar growing pains. I did. Drove me crazy for the first week. Then you figure out where the little obscure meta-gotchas are, and they never bother you again.) – Mars Mar 17 '16 at 04:54
  • Hmm... I wonder if it's just not compatible with clojure 1.6.0, which leiningen is currently feeding me. I can get it to work in boot. with `(set-env! :dependencies '[[net.mikera/core.matrix "0.50.0"]])` then `(use 'clojure.core.matrix)`, but after the first call it goes and fetches clojure 1.8.0... hmm... – Paul Gowder Mar 17 '16 at 05:02
  • ah! there it was! changed the dep in projects.clj to 1.8.0 and it runs. Well, that was an anticlimactic solution. Thanks for the clue in your dependencies list :-) – Paul Gowder Mar 17 '16 at 05:08
  • Great! Sometimes it's only through a comment discussion that the real problem reveals itself. I posted some of my remarks as an answer, and if you want, you can upvote it and/or accept it, but that's up to you. – Mars Mar 17 '16 at 05:15

1 Answers1

2

A classpath is a Java concept; Leiningen should set up the classpath correctly. What I suspect is that there's a mismatch between the directories, filenames, or namespace declarations. The file path should be <name passed to 'lein new'>/src/blabber/core.clj. It wasn't clear from what you wrote whether that's the case. Try running lein deps first, too, but you shouldn't need to do that. This and lein repl are usually run from the directory, i.e. the project root directory. You might need :source-paths or :main in project.clj, but I don't think so.

(use 'clojure.core.matrix) should work. Works for me, e.g. with

(defproject blabber "0.1.0-SNAPSHOT"
  :dependencies [[org.clojure/clojure "1.8.0"]
  [net.mikera/core.matrix "0.50.0"]]).
Mars
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