gistfile1.scala

Welcome to Scala version 2.10.0 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_51).
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scala> case class Foo(i: Int)
defined class Foo

scala> Vector(Foo(1), Foo(2), Foo(3))
res0: scala.collection.immutable.Vector[Foo] = Vector(Foo(1), Foo(2), Foo(3))

scala> res0 patch (from=-1, patch=Nil, replaced=1) // what's going on here ? from is a valid argument name
<console>:11: error: not found: value from
              res0 patch (from=-1, patch=Nil, replaced=1)
                          ^

// why does it delete the first element ? Is this expected ?
// this behavior makes it difficult to use this method in combination with
// indexWhere .. always need to have a check with "if" to see if it's a valid index
scala> res0 patch (-1, Nil, 1)  
res2: scala.collection.immutable.Vector[Foo] = Vector(Foo(2), Foo(3))

scala> res0 patch (from=0, patch=Nil, replaced=1)  // this is ok 
res4: scala.collection.immutable.Vector[Foo] = Vector(Foo(2), Foo(3))

should work as expected

res0 patch (from=(-1), patch=Nil, replaced=1) 

also

res0 patch (from= -1, patch=Nil, replaced=1)