Saturday, May 12, 2012

Scala is very nice - very very nice

Today I am gushing over Scala's par method and XML literals. I am fetching about 30,000 entries over REST calls. The server isn't super fast on this one, so each call takes a bit of time. Enter list.par stage left.

list.par creates a parallelizable list which given an operation will perform it in parallel across multiple CPUs.  It spawns threads and performs the operation, then joins all the results together at the end, very handy.

This little three letter method is turning what would be a very very long arduous process into a much less long one. Much much less.

val myList = io.Source.fromFile("list.txt") { x =>
  callService("FooService", "{id=\""+x"\"}")

It gets better. In Scala, XML can be declared as a literal. Not only that, but it runs inline like a normal literal, with a few special rules. This service is combining a bunch of json into an XML output.

val myOutput = io.Source.fromFile("list.txt") { x =>
  callService("FooService", "{id=\""+x"\"}")
}.map { x =>
  Json.parse[Map[String, Object]](x)("url").toString
}.map { x =>
    <url>{ x }</url>

Which I can now happily write to wherever I need to, a file, or a web service response. Nifty in the extreme.

In 2012, we live in a world of JSON and XML. Perl had it's day when text processing was king. Today, a language is needed that can cope with JSON, XML and Parallelization and still yield sane-looking code. I'm not a big Ruby fan, as anyone who knows me will tell you, but I'm willing to keep an open in. I'd like to see if Ruby can do this kind of thing as elegantly and easily and demonstrate it's a language for the web in 2012.  Also, I should mention Akka as well, though I don't yet know enough about it, other than it can allegedly take parallelization inter-compuer with similar simplicity.

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