I have recently started out with clojure, and I am using leiningen to create a small project. I am having troubles in getting leiningen to behave with command line arguments. The following is my src/project/core.clj
(ns project.core
(:gen-class))
(defn -main [& args]
(println (apply str args)))
and my project.clj
(defproject project "1.0.0-SNAPSHOT"
:description "FIXME: write"
:main project.core
:dependencies [[org.clojure/clojure "1.2.0"]
[org.clojure/clojure-contrib "1.2.0"]])
Now when I run lein run arg1 arg2, it gives me this error:
Exception in thread "main" java.lang.Exception: Unable to resolve symbol: arg1 in this context (NO_SOURCE_FILE:1)
at clojure.lang.Compiler.analyze(Compiler.java:5205)
at clojure.lang.Compiler.analyze(Compiler.java:5151)
at clojure.lang.Compiler$InvokeExpr.parse(Compiler.java:3057)
at clojure.lang.Compiler.analyzeSeq(Compiler.java:5371)
at clojure.lang.Compiler.analyze(Compiler.java:5190)
at clojure.lang.Compiler.analyze(Compiler.java:5151)
at clojure.lang.Compiler$BodyExpr$Parser.parse(Compiler.java:4670)
at clojure.lang.Compiler$FnMethod.parse(Compiler.java:4328)
at clojure.lang.Compiler$FnExpr.parse(Compiler.java:3173)
at clojure.lang.Compiler.analyzeSeq(Compiler.java:5367)
at clojure.lang.Compiler.analyze(Compiler.java:5190)
at clojure.lang.Compiler.eval(Compiler.java:5421)
at clojure.lang.Compiler.eval(Compiler.java:5415)
at clojure.lang.Compiler.eval(Compiler.java:5391)
at clojure.core$eval.invoke(core.clj:2382)
at clojure.main$eval_opt.invoke(main.clj:235)
at clojure.main$initialize.invoke(main.clj:254)
at clojure.main$null_opt.invoke(main.clj:279)
at clojure.main$main.doInvoke(main.clj:354)
at clojure.lang.RestFn.invoke(RestFn.java:422)
at clojure.lang.Var.invoke(Var.java:369)
at clojure.lang.AFn.applyToHelper(AFn.java:165)
at clojure.lang.Var.applyTo(Var.java:482)
at clojure.main.main(main.java:37)
Caused by: java.lang.Exception: Unable to resolve symbol: arg1 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)
... 23 more
However, if I do a lein uberjar and then do java -jar project-1.0.0-SNAPSHOT-standalone.jar arg1 arg2, I get the correct output.
arg1arg2
It isn't very comfortable to have to create the uberjar to run it every time while development, is there a better way?
This looks like it's caused by a bug that's been fixed in git. The fix will be in 1.4.2, which should be out in a few days. In the mean time, you can use workarounds discussed here: http://groups.google.com/group/clojure/msg/a8160b23a5019a12
From lein-run: "Args will be passed on as *command-line-args*"
So you will have to use those. The example on the site shows how. If you now what arguments you are passing you an also use :run-aliases to specify those in your project.clj. Again, the mentioned site has all the information.
My sample project.clj
(defproject addressbook "1.0.0-SNAPSHOT"
:description "FIXME: write"
:main addressbook.core
:run-aliases {:addressbook [addressbook.core -main "arg1"]}
:dependencies [[org.clojure/clojure "1.2.0"]
[org.clojure/clojure-contrib "1.2.0"]]
:dev-dependencies [[lein-run "1.0.0"]])
And the test code:
(ns addressbook.core
(:gen-class))
(defn -main [& [args]]
(if args (println args)))
Both "lein run addressbook foo" as "lein uberjar" work for me.
Related
I am trying my first run with ring and lein, and I am facing problems in getting it to run. I have taken this example from the book "Web development with Clojure", chapter 1, and also from https://quickleft.com/blog/your-first-clojure-web-app/ . The code from both these sites give me the same error - Class Not Found.
I have the following project.clj
(defproject myfirstwebapp "0.1.1"
:description "A hello world for a Ring based web app"
:dependencies [[org.clojure/clojure "1.8.0"]
[ring "1.4.0"]]
:plugins [[lein-ring "0.9.7"]]
:dev-dependencies [[lein-ring "0.9.7"]]
:ring {:handler myfirstwebapp.core/app})
And the following core.clj
(ns myfirstwebapp.core)
(defn app [req]
{:status 200
:headers {"content-Type" "text/html"}
:body "Hello World!"})
And the commands I ran were these:
lein new myfirstwebapp
edit project.clj as above
cd myfirstwebapp
lein deps
edit src/myfirstwebapp/core.clj as above
lein ring server
And now I am getting errors like:
Exception in thread "main" java.lang.ClassNotFoundException: leiningen.core.project$reduce_repo_step, compiling:(C:\Users\ROG\form-init7789757414629005682.clj:1:17608)
Is there some mismatch between the versions of different components that I am using? Or something else?
It is a bug in lein 2.6.0. Fixed in 2.6.1
I am following along with this example on creating a simple web service in Clojure using ring and jetty.
I have this in my project.clj:
(defproject ws-example "0.0.1"
:description "REST datastore interface."
:dependencies
[[org.clojure/clojure "1.5.1"]
[ring/ring-jetty-adapter "0.2.5"]
[ring-json-params "0.1.0"]
[compojure "0.4.0"]
[clj-json "0.5.3"]]
:dev-dependencies
[[lein-run "1.0.0-SNAPSHOT"]])
This in script/run.clj
(use 'ring.adapter.jetty)
(require '[ws-example.web :as web])
(run-jetty #'web/app {:port 8080})
And this in src/ws_example/web.clj
(ns ws-example.web
(:use compojure.core)
(:use ring.middleware.json-params)
(:require [clj-json.core :as json]))
(defn json-response [data & [status]]
{:status (or status 200)
:headers {"Content-Type" "application/json"}
:body (json/generate-string data)})
(defroutes handler
(GET "/" []
(json-response {"hello" "world"}))
(PUT "/" [name]
(json-response {"hello" name})))
(def app
(-> handler
wrap-json-params))
However, when I execute:
lein run script/run.clj
I get this error:
No :main namespace specified in project.clj.
Why am I getting this and how do I fix it?
You're getting this error because the purpose of lein run (according to lein help run) is to "Run the project's -main function." You don't have a -main function in your ws-example.web namespace, nor do you have a :main specified in your project.clj file, which is what lein run is complaining about.
To fix this, you have a few options. You could move the run-jetty code to a new -main function of the ws-example.web function and then say lein run -m ws-example.web. Or you could do that and also add a line :main ws-example.web to project.clj and then just say lein run. Or you could try using the lein exec plugin to execute a file, rather than a namespace.
For more info, check out the Leiningen Tutorial.
You have to put that (run-jetty) stuff into a -main somewhere and then add it to the project.clj like
:main ws-example.core)
From lein help run:
USAGE: lein run -m NAMESPACE[/MAIN_FUNCTION] [ARGS...]
Calls the main function in the specified namespace.
So, you would need to put your script.clj somewhere on the project source path and then call it as:
lein run -m script
I'm new to Clojure, and I don't quite understand how to write my project.clj so it works for both lein repl and lein run. Here it is (whole path: ~/my-project/project.clj):
(defproject my-project "1.0.0-SNAPSHOT"
:description "FIXME: write description"
:dependencies [[org.clojure/clojure "1.3.0"]]
:main my-project.core/hello
)
Then I have my ~/my-project/src/my_project/core.clj file
(ns my-project.core)
(defn hello []
(println "Hello world!")
)
lein run works just fine but I get a FileNotFoundException when running lein repl:
~/my-project$ lein run
Hello world!
~/my-project$ lein repl
REPL started; server listening on localhost port 42144
FileNotFoundException Could not locate hello__init.class or hello.clj on classpath: clojure.lang.RT.load (RT.java:430)
clojure.core=>
How should I edit the project.clj to solve this? Or do I have to call lein repl in a different way?
Thanks in advance.
EDIT: tried with lein deps and lein compile, but still the same error
~/my-project$ lein version
Leiningen 1.7.1 on Java 1.6.0_27 OpenJDK Client VM
~/my-project$ lein deps
Copying 1 file to /home/yasin/Programming/Clojure/my-project/lib
~/my-project$ lein compile
No namespaces to :aot compile listed in project.clj.
~/my-project$ lein repl
REPL started; server listening on localhost port 41945
FileNotFoundException Could not locate hello__init.class or hello.clj on classpath: clojure.lang.RT.load (RT.java:430)
One thing you could do to get it to work would be to change core.clj to:
(ns my-project.core
(:gen-class))
(defn hello []
(println "Hello world!"))
(defn -main []
(hello))
And edit the project.clj to:
(defproject my-project "1.0.0-SNAPSHOT"
:description "FIXME: write description"
:dependencies [[org.clojure/clojure "1.3.0"]]
:main my-project.core)
The (:gen-class) will tell the compiler to generate a Java class for the namespace, and the :main directive in project.clj will tell lein run to run the main method on the class, which is given by -main. Why lein repl was failing to find my-project.core/hello is unclear to me, but I don't know much about leiningen internals.
I've created a simple example using:
%> lein new lein-check
I've only modified the code so that it now has a 'main':
(defproject lein-check "0.1.0-SNAPSHOT"
:description "FIXME: write description"
:url "http://example.com/FIXME"
:license {:name "Eclipse Public License"
:url "http://www.eclipse.org/legal/epl-v10.html"}
:main "lein-check.core"
:dependencies [[org.clojure/clojure "1.4.0"]])
(ns lein-check.core
(:gen-class))
(defn -main
"I don't do a whole lot."
[& args]
(println "Hello, World!"))
But the first time I run lein uberjar even after a clean I get this:
Compiling lein-check.core
Exception in thread "main" java.lang.ClassCastException:
java.lang.String cannot be cast to clojure.lang.Symbol
at clojure.core$find_ns.invoke(core.clj:3659)
at clojure.core$load_one.invoke(core.clj:5228)
at clojure.core$compile$fn__4895.invoke(core.clj:5426)
at clojure.core$compile.invoke(core.clj:5425)
at user$eval7.invoke(NO_SOURCE_FILE:1)
at clojure.lang.Compiler.eval(Compiler.java:6511)
at clojure.lang.Compiler.eval(Compiler.java:6501)
at clojure.lang.Compiler.eval(Compiler.java:6477)
at clojure.core$eval.invoke(core.clj:2797)
at clojure.main$eval_opt.invoke(main.clj:297)
at clojure.main$initialize.invoke(main.clj:316)
at clojure.main$null_opt.invoke(main.clj:349)
at clojure.main$main.doInvoke(main.clj:427)
at clojure.lang.RestFn.invoke(RestFn.java:421)
at clojure.lang.Var.invoke(Var.java:419)
at clojure.lang.AFn.applyToHelper(AFn.java:163)
at clojure.lang.Var.applyTo(Var.java:532)
at clojure.main.main(main.java:37)
Compilation failed: Subprocess failed
Running a follow up uberjar though successfully creates the jars:
Created ....\lein-check-0.1.0-SNAPSHOT.jar
Including lein-check-0.1.0-SNAPSHOT.jar
Including clojure-1.4.0.jar
Created ....\lein-check-0.1.0-SNAPSHOT-standalone.jar
Is uberjar sometimes running the main after a completion? Is it supposed to do that? I'm not quite sure if this is a user error, a lein bug or a clojure bug.
The problem is in the line
:main "lein-check.core"
It should be
:main lein-check.core
You're using a string instead of a symbol.
Well it turns out that the Lein Sample Project show the :main as a symbol and not a string. Once this was updated then running lein uberjar works as expected.
This line in particular:
:main "lein-check.core"
changed to:
:main 'lein-check.core
I am working through the book Programming Clojure (Second Edition) by Stuart Halloway and Aaron Bedra. As instructed in the book, I edit and add code in the file project.clj (which was created by lein new pinger) so that it reads:
(defproject pinger "0.0.1-SNAPSHOT"
:description "A website availability tester"
:dependencies [[org.clojure/clojure "1.3.0"]])
(ns pinger.core
(:import (java.net URL HttpURLConnection)))
(defn response-code [address]
(let [conn ^HttpURLConnection (.openConnection (URL. address))
code (.getResponseCode conn)]
(when (< code 400)
(-> conn .getInputStream .close))
code))
I then try to load the file and get the following error:
user=> (load-file "src/pinger/project.clj")
CompilerException java.lang.RuntimeException: Unable to resolve symbol: defproject
in this context, compiling:(C:\Documents and Settings\vreinpa\My Documents\Books\ProgrammingClojure\code\src\pinger\project.clj:1)
What am I doing wrong here?
You're not supposed to add any code to the project.clj outside of the defproject definition.
The real project code is supposed to go into the classpath (for instance, in the files generated by "lein new ..." in src)