Posts Tagged ‘java’

Invoking Clojure code from Java

Posted: December 24, 2012 in Uncategorized
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I often see people trying to call Clojure code from Java and having some trouble doing this. So I decided to write a quick utility to do this (inspired by Rich Hickey’s Lightening Talk), and provide a simple example.



Something I still love about Java

Posted: September 6, 2012 in coding
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Clojure is certainly my language of choice nowadays.

But recently I spent a day working on an old ~35k LOC Java code base, and it reminded me what I still love about Java.


Clojure performs exceptionally well considering it is a dynamic language.

My rule of thumb is:

  • It’s 5-10x slower than optimised Java if you write idiomatic Clojure (with liberal use of higher order functions, lazy sequences and all that goodness)
  • It’s about the same speed as Java if you really optimise hard – you can basically generate approximately the same JVM bytecode.

This StackOverflow question prompted me to write a quicksort implementation in Clojure, which I’ve included here to demonstrate that matching Java speed is entirely possible within Clojure.

Warning against premature optimisation:┬áthis is not pretty code. You shouldn’t be writing code like this unless you have profiled your code and identified a real performance issue.


On mixing Clojure and Java

Posted: August 8, 2012 in Uncategorized
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Clojure is currently my language of choice for new projects. The reasons probably won’t come as a surprise – among other things I love the expressive style, the level of productivity which enables you to “get things done”, the interactive development at the REPL, the meta-programming capabilities, the approach to concurrency and the various advantages of functional programming.

Yet in several recent projects, I’ve found myself using a polyglot mix of Clojure and Java.

Why would I subject myself to this?