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Tackling my first Clojure project, a Graphical HTTP Benchmarker in Clojure

55 points by andrewvc 15y ago

ibdknox 15y ago
Cool project! I looked over your code very briefly and noticed you don't tend to use destructuring very much. It was something that took me a while to get used to too, but it turns out to be very useful and makes the code much smaller. Take for example this: (defn stats [requests-state] "Returns a mapping of RequestsState http states states to counts" (reduce (fn [stats request] (let [r @request state (:state r) status (:status r) statuses (:statuses stats)] (assoc stats :total (inc (stats :total 0)) state (inc (stats state 0)) :statuses (assoc statuses status (inc (statuses status 0))) :progress (if (not= state :untried) (inc (stats :progress 0)) (stats :progress 0))))) {:statuses {}} (flatten (:grid @requests-state)))) Could be written like so: (defn stats [requests-state] "Returns a mapping of RequestsState http states states to counts" (reduce (fn [{statuses :statuses total :total :as stats} request] (let [{state :state status :status} @request] (assoc stats :total (inc (or total 0)) state (inc (stats state 0)) :statuses (assoc statuses status (inc (statuses status 0))) :progress (if (not= state :untried) (inc (stats :progress 0)) (stats :progress 0))))) {:statuses {}} (flatten (:grid @requests-state))))
- andrewvc 15y ago
  Thanks for the tip! That's much better, I'll merge that in later today.
- ataggart 15y ago
  You can also avoid the duplicated key/sym names: (fn [stats request] (let [{:keys [statuses total]} stats {:keys [state status]} @request] ...))
joevandyk 15y ago
I'd love to get more into Scala and Clojure, but I don't know the first thing about Java, especially the Java ecosystem (war's, ant, jvm's, etc). Unfortunately, most books/articles on Clojure and Scala assume you know Java.
- ddkrone 15y ago
  Download eclipse and just get started if you want to learn java. It's got plugins for practically everything and you can learn the low level details when it becomes necessary.
- ibdknox 15y ago
  I can't comment on Scala, but I think Clojure is starting to get to the point where you can learn just Clojure and not have to think about Java until much later. At some point you'll assuredly interact with Java some, but there are a ton of libs out there now that are simple Clojure wrappers around most common things. Really, to get started with Clojure, all you need to do is install Leiningen (https://github.com/technomancy/leiningen https://github.com/technomancy/leiningen) and type "lein repl" in a terminal window. No ant, wars, or jvm's to think about :)
- andrewvc 15y ago
  Yeah, I may have overstated the case for Java a bit. You don't need to be a Java expert, but you should know enough Java to be able to create your own classes, and make simple little programs with multiple classes. Really though, you should know how to browse javadocs, and the java ecosystem. It is true that you can use clojure wrappers around java libs (and its nicer too) but a lot of them don't expose the full functionality of their java counterparts, and clojure's young enough that to understand how they work you'll have to dive heavily into their java interop.
- technomancy 15y ago
  Knowing how to write Java is absolutely not needed at all. Knowing how to read Java can be useful depending on what libraries you need. The one thing that you have to learn no matter what is the basic IO classes, which are covered pretty well in http://copperthoughts.com/p/clojure-io-p1/ http://copperthoughts.com/p/clojure-io-p1/. Before the clojure.java.io namespaces was created, it used to be necessary to interact directly with those classes for even basic usage. (Kids these days! They've got it so easy.) The web application ecosystem can be a bit intimidating to peace-loving programmers with all its talk of wars, but even that is changing with deployment options like Elastic Beanstalk and Heroku. Anyway, you hear horror stories about Enterprise Java Beans, dependency injection frameworks, Maven, and whatnot, but you never see any of that in everyday Clojure.
daveray 15y ago
Good stuff. I'm not sure if this is an improvement, but it's a nice piece of trivia... your status range checks can be reduced a bit: (and (>= status 200) (< status 300)) becomes: (<= 200 status 299) Go Clojure.
- andrewvc 15y ago
  Very cool. It's not an easy call, as its esoteric syntax, but I think I'll put it in.

55 points by andrewvc 15y ago

Cool project! I looked over your code very briefly and noticed you don't tend to use destructuring very much. It was something that took me a while to get used to too, but it turns out to be very useful and makes the code much smaller. Take for example this: (defn stats [requests-state] "Returns a mapping of RequestsState http states states to counts" (reduce (fn [stats request] (let [r @request state (:state r) status (:status r) statuses (:statuses stats)] (assoc stats :total (inc (stats :total 0)) state (inc (stats state 0)) :statuses (assoc statuses status (inc (statuses status 0))) :progress (if (not= state :untried) (inc (stats :progress 0)) (stats :progress 0))))) {:statuses {}} (flatten (:grid @requests-state)))) Could be written like so: (defn stats [requests-state] "Returns a mapping of RequestsState http states states to counts" (reduce (fn [{statuses :statuses total :total :as stats} request] (let [{state :state status :status} @request] (assoc stats :total (inc (or total 0)) state (inc (stats state 0)) :statuses (assoc statuses status (inc (statuses status 0))) :progress (if (not= state :untried) (inc (stats :progress 0)) (stats :progress 0))))) {:statuses {}} (flatten (:grid @requests-state))))

andrewvc 15y ago
Thanks for the tip! That's much better, I'll merge that in later today.
ataggart 15y ago
You can also avoid the duplicated key/sym names: (fn [stats request] (let [{:keys [statuses total]} stats {:keys [state status]} @request] ...))

joevandyk 15y ago

I'd love to get more into Scala and Clojure, but I don't know the first thing about Java, especially the Java ecosystem (war's, ant, jvm's, etc). Unfortunately, most books/articles on Clojure and Scala assume you know Java.

ddkrone 15y ago
Download eclipse and just get started if you want to learn java. It's got plugins for practically everything and you can learn the low level details when it becomes necessary.
ibdknox 15y ago
I can't comment on Scala, but I think Clojure is starting to get to the point where you can learn just Clojure and not have to think about Java until much later. At some point you'll assuredly interact with Java some, but there are a ton of libs out there now that are simple Clojure wrappers around most common things. Really, to get started with Clojure, all you need to do is install Leiningen (https://github.com/technomancy/leiningen https://github.com/technomancy/leiningen) and type "lein repl" in a terminal window. No ant, wars, or jvm's to think about :)
andrewvc 15y ago
Yeah, I may have overstated the case for Java a bit. You don't need to be a Java expert, but you should know enough Java to be able to create your own classes, and make simple little programs with multiple classes. Really though, you should know how to browse javadocs, and the java ecosystem. It is true that you can use clojure wrappers around java libs (and its nicer too) but a lot of them don't expose the full functionality of their java counterparts, and clojure's young enough that to understand how they work you'll have to dive heavily into their java interop.
technomancy 15y ago
Knowing how to write Java is absolutely not needed at all. Knowing how to read Java can be useful depending on what libraries you need. The one thing that you have to learn no matter what is the basic IO classes, which are covered pretty well in http://copperthoughts.com/p/clojure-io-p1/ http://copperthoughts.com/p/clojure-io-p1/. Before the clojure.java.io namespaces was created, it used to be necessary to interact directly with those classes for even basic usage. (Kids these days! They've got it so easy.) The web application ecosystem can be a bit intimidating to peace-loving programmers with all its talk of wars, but even that is changing with deployment options like Elastic Beanstalk and Heroku. Anyway, you hear horror stories about Enterprise Java Beans, dependency injection frameworks, Maven, and whatnot, but you never see any of that in everyday Clojure.

daveray 15y ago

Good stuff. I'm not sure if this is an improvement, but it's a nice piece of trivia... your status range checks can be reduced a bit: (and (>= status 200) (< status 300)) becomes: (<= 200 status 299) Go Clojure.

andrewvc 15y ago
Very cool. It's not an easy call, as its esoteric syntax, but I think I'll put it in.