Pru

Frustrated by bloated, slow, and overly complicated XML and JSON writing libraries? Pru is the simplest thing that could possibly work--a small (less than 100 lines) collection of combinators that build up a StringBuilder => Unit (newtyped as Action). It has zero dependencies. Here's a simple example of its use:

import pru.write.{JSON => J, XML => X, Writer => W}

val xml = X.Nest("foo") { X.LeafTag("bar", "id" -> "1", "bar" -> "2") }

val json = J.List(
  J.literal("uno"),
  J.literal("dos"),
  J.literal("tres")
)

val xml2 = xml ++ xml
val json2 = J.List(json, json)

println(xml)
println(xml2)
println(json2)

This produces:

<foo><bar id="1" bar="2"/></foo>
<foo><bar id="1" bar="2"/></foo><foo><bar id="1" bar="2"/></foo>
[["uno", "dos", "tres"], ["uno", "dos", "tres"]]

By convention, functions starting with a capital letter are variadic (for instance, J.List above), while function starting with a lowercase letter of the same name accept an ordinary Seq input.

Things this library does not do

• Pretty-printing: Everything goes on one line.
• Produce XML or JSON documents that don't fit in memory: You are building up a function which updates a StringBuilder, so streaming a huge document is not recommended. Of course, you can use this library to produce individual chunks of a large stream.
• Implicit derivation of XML or JSON serialization code: There is no typeclass magic whatsoever, just regular combinators, invoked explicitly. Nothing stops you from building up a collection of implicit A => Action values if you're so inclined.

Where to get it

Add the following to your sbt build:

resolvers += "Bintray Repo" at "http://dl.bintray.com/pchiusano/maven"

libraryDependencies += "pru" %% "pru" % "0.4"

There are builds against Scala 2.10.3 and Scala 2.11.

Documentation

Just read the source. It's less than 100 lines. The type signatures and a REPL session should tell all you need to know!