PyRuby blog » scala http://www.pyruby.com Just another WordPress weblog Mon, 12 Dec 2011 11:03:27 +0000 en hourly 1 http://wordpress.org/?v=3.1.2 Scala JSON Generator http://www.pyruby.com/2010/04/29/scala-json-generator/ http://www.pyruby.com/2010/04/29/scala-json-generator/#comments Fri, 30 Apr 2010 05:56:08 +0000 PyRuby http://www.pyruby.com/?p=72 I am working with Scala more and more at the moment. I find it a really powerful and fun language to work in. One of the recent tasks has been to translate various tab delimited data files into a common JSON format. In java land, I’ve used Jackson to great effect, but [...]]]> I am working with Scala more and more at the moment. I find it a really powerful and fun language to work in. One of the recent tasks has been to translate various tab delimited data files into a common JSON format. In java land, I’ve used Jackson to great effect, but it really doesn’t feel very Scala. My colleague and I were busy following the Jackson route and had a working implementation, but it just didn’t feel clean, simple and Scala idiomatic. That’s when we decided to define how we thought the api should work.

One of the great things about using Scala, is it’s a fantastic language for creating DSLs. When I really don’t like the way the code that solves a specific problem looks, I like to write the pseudo code that feels right, and then figure out how to make that work. With Scala, I have had a great deal of success in this approach. We started off defining a JSON generator DSL that looked like this:-

  1. def mapToJson(myMap: Map[String, String]) = {
  2.   val json = jsonObject {
  3.     field("cheese", myMap.get("name")
  4.     jsonObject("Score") {
  5.       field("aroma", myMap.get("smell")
  6.       field("flavor", myMap.get("taste")
  7.       field("texture", myMap.get("squidginess")
  8.     }
  9.     jsonArray("servedOn") {
  10.       jsonObject {
  11.         field("cracker", myMap.get("crackerType")
  12.         field("maker", myMap.get("crackerMaker")
  13.       }
  14.     }
  15.     jsonArray("sampledOn") {
  16.       value(myMap.get("firstTried")
  17.       value(myMap.get("secondTried")
  18.       value(myMap.get("thirdTried")
  19.     }
  20. }

There was another case for jsonArray, which doesn’t involve having a field name, i.e. jsonArray { … }. Whilst attempting to find a way to implement the DSL that would satisfy this, we had to make a small compromise. The call jsonObject {…} and jsonObject(“fieldName”) {…} caused problems because the signatures of the DSL methods were indistinguishable when using them. The compromise we struck on was jsonObject() {…} and jsonObject(“fieldName”) {…}, i.e. just adding the empty parenthesis. This then is the resulting syntax, and the implementation can be found here.

This is a first cut, but as this library was introduced to solve a problem in our production app. It will be tweaked and maintained so any bugs or extra features will quickly get incorporated.

]]> http://www.pyruby.com/2010/04/29/scala-json-generator/feed/ 4 Writing Scala code in IntelliJ IDEA http://www.pyruby.com/2009/10/15/writing-scala-code-in-intellij-idea/ http://www.pyruby.com/2009/10/15/writing-scala-code-in-intellij-idea/#comments Fri, 16 Oct 2009 04:00:47 +0000 PyRuby http://www.pyruby.com/?p=39 Just read that IntelliJ IDEA 9 will be split into a Community Edition, and an Ultimate Edition. The Community Edition will be open sourced, and allows the Scala plugin. I’ve been writing Scala code for a few months now, and using IDEA in the office, and TextMate at home. I’m really hoping [...]]]> Just read that IntelliJ IDEA 9 will be split into a Community Edition, and an Ultimate Edition. The Community Edition will be open sourced, and allows the Scala plugin. I’ve been writing Scala code for a few months now, and using IDEA in the office, and TextMate at home. I’m really hoping that I’ll be able to use the open sourced version at home so I don’t have to context switch so much. I’ve tried the Scala plugin for NetBeans, but it is so far off ready, that I prefer using TextMate. I know the scala plugin for IDEA 8.1 works really well, but it doesn’t work in the IDEA 9.0 early access release yet. I hope this gets fixed soon so I can play with scala at home more.

NOTE: I don’t recommend using maven with Scala on the Mac, because it just doesn’t play nicely. Don’t know why, but it’s broken to the point that I no longer even try to use Maven to build my scala code.

]]> http://www.pyruby.com/2009/10/15/writing-scala-code-in-intellij-idea/feed/ 1