Scala: desugaring

This post is composed of the info on scala source desugaring originating from this thread. I was afraid the information would be lost forever so, after a fight with markdown and pandoc I produced this:

Desugaring of scala types

Source type	Type
Int => Int	Function1[Int, Int]
(Int, Int, Int) => Int	Function3[Int, Int, Int, Int]
(String, Int)	Tuple2[String, Int]
String <:< Test	<:<[String, Test]

Desugaring of scala values

Source value	Desugared	Type
null	Null	Null
()	()	Unit
1	1	Int
2.0f	2.0f	Float
3.0	3.0	Double
"hello"	"hello"	String
'd	Symbol("d")	Symbol
(5,6)	Tuple2(5,6)	Tuple2[Int, Int]
(7,8,9)	Tuple3(7,8,9)	Tuple3[Int, Int, Int]

Now lets get down to functions (first line - source, second - desugared, optional third - type):

Anonymous Function1

x: Int => x * 1

new Function1[Int, Int] {
    def apply(x: Int): Int = x * 1
}

Anonymous Function2

(_: Int) * (_: Int)

(x1: Int, x2: Int) => x1 * x2

Type: Function2[Int, Int, Int]

Partial function explicitly typed as a Function1

{ case x: Int => x }: (Any => Int)

new Function1[Any, Int] {
   def apply(x: Any) = x match { case x: Int => x}
}

Partial function

{ case x: Int => x }: PartialFunction[Any, Int]

new PartialFunction[Any, Int] {
   def apply(x: Any) = x match { case x: Int => x}
   def isDefinedAt(x: Any) = x match { case x: Int => true; case _ => false}
}

XML Syntax

<a:b><c></c></a:b>

new xml.Elem("a", "b", null, xml.TopScope,
new xml.Elem(null, "c", null, xml.TopScope))

Type: xml.Elem 

Thanks to:

• David Flemstrom
• Johannes Rudolph
• Jason Zaugg