scala.Predef

• object scala.Predef
• Predef$ArrowAssoc#-> has been defined with @inline.
• @inline locally[T](x: T): T = x
  object X{
    class Foo
    {
      println("in the definition of Foo")
    }
    class Bar
    locally{
      println("not in the definiton of Bar")
    }
  }
  new X.Foo; new X.Bar
  

scala.Option

• trait scala.Option
  
• Option.apply(null) or Option(null) // => None
  Option.apply(1) or Option(1)     // => Some(1)
• trait scala.Option
• None orNull           // => null
  Some(1) orNull      // => 1

scala.FunctionX

• Since 2.8, FunctionX.tuple has been added. As for Scala 2.7, use Function.tupled
• case class A(x:Int, y:Int)
  val x = A.apply _
  x.tupled(1->2)

scala.io.PartialFunction

• object scala.PartialFunction
  
• import PartialFunction._
  def strangeConditional(other: Any): Boolean = cond(other) {
    case x: String if x == "abc" || x == "def"  => true
    case x: Int => true
  }
• import PartialFunction._
  def onlyInt(v: Any): Option[Int] = condOpt(v) { case x: Int => x }
• trait scala.PartialFunction
• {{case x if x.length> 0 => x.length}:PartialFunction[String, Int]} lift "" // => None
  

scala.runtime.AbstractFunctionX

• I implemented AbstractionFunction0-22, motivated by this discussion...
• anonymous functions willl be defined with AbstractFunctionX.
• $ echo 'class X{Nil map identity}' > foo.scala; scalac -Xprint:cleanup foo.scala
  

Collections

• trait scala.collection.SeqLike
  
• (0 to 5) sortWith {_>_} toList // => List(5, 4, 3, 2, 1, 0)
  
• "ABC" sortBy {'Z'-_} // => "CBA"
• "aabbaabbaa" indexOfSlice "ab" // => 1
• "aabbaabbaa" lastIndexOfSlice "ab" // => -1 ??? Ticket 3455
  
• ("abc" corresponds "ABC") {_.toUpper==_} // => true
• "aBc" indexWhere(_.isUpper) // => 1
• "aBc" lastIndexWhere(_.isUpper) // => 1
• "aBBc" segmentLength(_.isUpper, 1) // => 2
• "BBc" prefixLength(_.isUpper) // => 2 ; def prefixLength(p: A => Boolean) = segmentLength(p, 0)
• "abc" updated( 1, 'B') // => "aBc"
• "abcXXXXdef" patch(3, "YYY", 4)  // => "abcYYYdef"
• "abc" padTo(5, '!') // => "abc!!"
• "abc" indices // => Range(0, 1, 2)
• "abbc" distinct // => "abc"
• "abc" union "def" // => "abcdef"
• "abc" diff "ac" // => "b"
• "abcdef" intersect "bcd" // => "bcd"
• "ab" :+ 'c' // => "abc"
  
• 'a' +: "bc" // => "abc"
• "abc" zipWithIndex // => Vector(('a',0), ('b',1), ('c',2))
• "abc" zip "def" // => Vector(('a',0), ('b',1), ('c',2))
• "abc" tail // => "bc"
• "abc".reverseIterator.toList // => List('c', 'b', 'a')
• "abc" reverseMap{_.toUpper} // => "CBA"
• trait scala.collection.TraversableLike
• List(1,1,2,5,5,5) groupBy identity mapValues (_.size) // => Map((1,2), (2,1), (5,3))
  
• "" nonEmpty // => false
• "abc" head // => 'a'
• "aBc" filterNot {_.isUpper} // => "ac"
• List(1,"2",3) collect {case c:String => c} // => List(2)
• (0 to 10) withFilter { _%2==1 } map identity // => Vector(1, 3, 5, 7, 9)
• val x = for(i<-(0 to 10)) yield { println(i); i }
  
val x = for(i<-(0 to 10).view) yield { println(i); i } ; x(0); x(1)
• trait scala.collection.MapLike
• List(1,1,2,5,5,5) groupBy identity mapValues (_.size) // => Map((1,2), (2,1), (5,3))
  
• trait scala.collection.IndexedSeqOptimized
  
• Map((1->2),(2->3)) span {case(k,v) => k%2==1} // => (Map(1 -> 2),Map(2 -> 3))
• "abc" splitAt 1 // => (a,bc)
  
• trait scala.collection.Iterator
  
• (1 to 5).iterator.sliding(3).toList  // => List(List(1, 2, 3), List(2, 3, 4), List(3, 4, 5))
  
• (1 to 5).iterator.sliding(4, 3).toList // => List(List(1, 2, 3, 4), List(4, 5))
  
• (1 to 5).iterator.sliding(4, 3).withPartial(false).toList // => List(List(1, 2, 3, 4))
  
• val it2 = Iterator.iterate(20)(_ + 5)
  (1 to 5).iterator.sliding(4, 3).withPadding(it2.next).toList // => List(List(1, 2, 3, 4), List(4, 5, 20, 25))
• (1 to 7).iterator grouped 3 toList    // => List(List(1,2,3),List(4,5,6),List(7))
• (1 to 7).iterator grouped 3 withPartial false toList  // => List(List(1,2,3), List(4,5,6))
• val it2 = Iterator.iterate(20)(_ + 5)
  (1 to 7).iterator grouped 3 withPadding it2.next toList // => List(List(1, 2, 3), List(4, 5, 6), List(7, 20, 25)
• (0 to 10) sameElements (10 to 0 by -1).reverse // => true
• (0 to 4) partition {_>2} // => (IndexedSeq(3, 4),IndexedSeq(0, 1, 2))
• object scala.collection.Iterator
  
• Iterator.fill(3)(0) toList // => List(0, 0, 0)
• trait scala.collection.IterableLike
• "foo.jpg" dropRight 4 => // "foo"
• "foo.jpg" takeRight 3 => // "jpg"
• "abc".iterator.toSeq => ArrayBuffer('a', 'b', 'c')
• "abc" zipAll ("AB", "x", "X") // => Vector((a,A), (b,B), (c,X))
• trait scala.collection.TraversableOnce
  
• (1 to 10) sum // => 55
  
• (1 to 10) product // => 3628800
  
• (1 to 10) min // => 1
  
• (1 to 10) max // => 10
• (1 to 10) count { _%2==1 } // => 5
  
• Array.empty[Int].reduceLeftOption(_+_) // => None
• val x:List[Int] = Nil; x.reduceRightOption(_+_) // => None
• List((1->2),(3->4)).toMap // => Map((1,2), (3,4))
• List((1->2),(3->4)).toSet // => Set((1,2), (3,4))
• List((1->2),(3->4)).toMap.toList // => List((1,2), (3,4))
• "abc" toIterable // => abc in Iterable[Char]
• "abc" toIndexedSeq // => ArrayBuffer(a, b, c)
• "abc" toStream // => Stream(a, ?)
  
• trait scala.collection.TraverableLike
• Map().stringPrefix // => Map
• trait scala.collection.generic.GenericTraversableTemplate
• (0 to 3) unzip {p => (p, -p)} // => (Vector(0, 1, 2, 3),Vector(0, -1, -2, -3))
• List(List(1, 2, 3), List(4, 5), List(6, 7, 8)) transpose // => List(List(1, 4, 6), List(2, 5, 7), List(3, 8))
• abstract class scala.collection.generic.TraversableFactory
• List.tabulate[Int](3, 3)(_ * _) // => List(List(0, 0, 0), List(0, 1, 2), List(0, 2, 4))
  
• trait scala.collection.immutable.List
• xs reverse_::: ys is equivalent to xs.reverse ::: ys but is more efficient.
• trait scala.collection.immutable.StringLike
• "foo.jpg" stripPrefix "foo" // => "jpg"
  
• "foo.jpg" stripSuffix ".jpg" // => "foo"
• "%d" formatLocal(java.util.Locale.US, 1)  // => "1"
• object scala.collection.mutable.Array
• Array.ofDim[Int](1,2,3) // => Array(Array(Array(0, 0, 0), Array(0, 0, 0)))
• class scala.collection.immutable.Vector
  
• Available Methods for String on Scala 2.7 & 2.8
• The previously deprecated method List.+ has been removed on 2.8.
• the deprecated methods in 2.8, compiled by @jorgeortiz85, http://tinyurl.com/yzrk6e7 ,http://tinyurl.com/ygxam39