Hi I have some helper fns I want to load into the user ns for a lein repl on startup across all my projects.
What's the recommended way to do this as lein plugin?
Failing that I tried to make a ~/lein/user.clj and to my surprise that did't work? $Project/user.clj works fine but I don't want to copy to each project.
Take a look at vinyasa, which allows you to do exactly that.
Related
I am thinking of creating an educational program in Clojure that would show a console where the user could edit code in order to change a running code in another part of the screen (like a game, for instance). Would that be possible? If so, what should I study in order to be able to do this?
It is possible. See this Interactive programming Flappy Bird in ClojureScript . It uses clojurescript and figwheel as its development environment.
The awesome thing about figwheel is that you can change the flappybird running code in the browser by simply evaluating new code in the repl and then figwheel push the new code to the browser. The changes happened in real time.
You can start studying clojure and clojurescript.
Hm, changing code during runtime is one of the basic concepts behind clojure.
Watch this for more on this topic: https://www.youtube.com/watch?v=P76Vbsk_3J0
Otherwise every repl or form of a repl can do that.
To get started have a look at Lighttable: http://lighttable.com/ It has inline evaluation in the editor.
Beginner here.
Can I compile an existing Clojure script to run it on the web using ClojureScript?
Let's say that I have a script that prints Hello world in my terminal, and I want to print that text on the browser. Should I rewrite a whole script with ClojureScript syntax, or should I just compile it using another compiler?
(ns clojure-hello-world.core
(:gen-class))
(defn -main [& args]
(println "Hello World"))
(Long answer :P)
Even though Clojure and ClojureScript share a good amount of features, there are some that are specific to one or the other. For example there are no real classes in JavaScript so the :gen-class specification in the ns form doesn't make much sense.
One important fact is that the syntax of both Clojure and ClojureScript is exactly the same, differences have to do mostly with the host VM in which they run (Java VM in the case of Clojure and JavaScript VM in the case of ClojureScript).
There is a list of the differences between the two Clojure implementations here.
There's also a tool called cljx to "write a portable codebase targeting Clojure/ClojureScript". Recently there has been some discussion on the Clojure Dev group around finally implementing feature expressions which would on one hand deprecate the use of cljx but on the other complicate the work that tools have to do to extract information from Clojure source files.
I would start with lein-cljsbuild to get started. This will get you going with a nice edit eval and look at browser loop. It's well worth getting this setup first because it makes learning ClojureScript much more fun. I promise it's worth the hassle. If you need more interactive support the folks in #clojure on freenode are very kind and helpful.
Basically, the Browser executes JavaScript. You compile your ClojureScript code to JavaScript. The Browser loads your JavaScript via an HTML page. So, you have to create an HTML Page and point your Browser at it.
The simplest way I got started was to use Luminous (http://www.luminusweb.net/docs/clojurescript.md).
However, Chestnut (https://github.com/plexus/chestnut) looks promising.
I'm using Austin to set up a browser-connected REPL, and following the example of its sample project, which uses Enlive to add the REPL script to the page.
Now I'd like to deploy my app, but I don't wan't Austin or my REPL to be on the page in production. What's the intended way to use the REPL only in development?
Is there a way to use Enlive as a middleware I could use in development and not in production?
There's almost always something that uniquely distinguishes a production environment from :dev that you can use as a conditional: if in :dev, inject the result of (browser-connected-repl-js); if not, don't.
If your deployment environment doesn't have such a property, I'd suggest adding one, as this sort of "only in environment X" use case is pretty common for a lot of things.
On the other hand, if you're looking to avoid having Austin and its dependencies included in your production-targeted builds entirely without changing any of your code that uses browser-connected-repl-js, one solution might be to simply dummy up the relevant Austin namespace, e.g.:
(ns cemerick.austin.repls)
(defn browser-connected-repl-js [& _] "")
Put that in cemerick/austin/repls.clj in a directory that is included in your project.clj's non-:dev profile:source-paths. Now your code will deploy to production without Austin and its dependencies, and your code will transparently call the above dummy function (injecting nothing into your page(s)).
In my clojurescript code I have the following:
(defn onload [] (repl/connect "http://localhost:9000/repl"))
(set! (.-onload js/window) onload)
The Clojurescript repl is very useful in development, but I am hesitant to leave it in the code during production. What is the cleanest way to have the above code present during development (simple compilation), but absent during production (advanced compilation)?
The modern-cljs tutorial actually describes exactly how to solve this here.
Hope that helps!
Unfortunately there aren't currently any well defined ways to do conditional compilation in ClojureScript.
You could add configuration variables to control whether to start a REPL in a variety of ways, but one quick and easy way would be to get the hostname of the current page, and only invoke repl/connnect if it was "localhost" or whatever other domains you're using for development work.
I think a combination of lein2 profiles and cljsbuild src-paths munging can do the trick. eg, create a namespace that simply loads your repl, and exclude it with a profile run for the final compile (possibly might need to create a dummy namespace in another src-path directory).
I occasionally get this problem, and generally work around it, but it's rather frustrating.
I have all of Incanter (check it out if you don't know it: it's superb) on my classpath. I try to import it (through a Slime REPL) like this: user> (use 'incanter.core), but fail.
Doing this: user> (use 'clojure.contrib.def) works just fine, and this file is in the same place–on my classpath.
Regardless, the error isn't anything about classpath: it's this:
Don't know how to create ISeq from: clojure.lang.Symbol
[Thrown class java.lang.IllegalArgumentException]
You can see my entire terminal here (a screenshot.)
I don't know what's going on here, and it's really frustrating, as I really would like to use Incancter, and I can from the Incanter binary's REPL. I definitely don't want to develop from that–and this should work.
Any help would be much appreciated.
EDIT:
It appears as though Incanter requires Clojure 1.2, and lein swank gives me Clojure 1.1. This might be the cause of my problems: if so, is there a way to continue to use Swank & Lein with Clojure 1.2?
Thanks again!
EDIT:
Apparently if you start using Clojure-1.1 and lein swank, you're stuck with it unless you make a new project.
If future people have this problem, this article helped me out, but also, at least for me, you must start a new lein project if you had begun it using leink swank and Clojure-1.1. Simply changing your project.clj file and then lein swanking again doesn't work.
Yes, you can use Leiningen and swank-clojure with Clojure 1.2. You might need to use a recent version of Leiningen (I'm not sure if a certain old limitation affected lein repl only or was it lein swank as well; anyway, try the 1.2-RC2 which you'll find in the downloads section on GitHub). You will also need to use a recent-enough swank-clojure; I use a bleeding edge checkout myself, get yours here.
Other than that, simply use 1.2 jars for Clojure and contrib. (Lein uses it's own Clojure, separate from the one used for lein swank, for its internal workings and you never need to care about it; swank-clojure has no AOT'd namespaces and doesn't particularly care about the Clojure version, except once in a (long!) while something breaks, a patch is applied and joy is restored.)
I hope the above helps, but if it doesn't: your problem description is not entirely sufficient for me to get a clear picture of what is happening. Could you add information on what it means for "all of Incanter" to be on your classpath (do you mean the jars? sources? where do you get them? how do you set your classpath?). Without knowing this, it'll be hard to replicate your setup to try to track down the source of the problem.
Of course if bumping some versions fixes things, please disregard my current confusion. ;-)