Which operations should be included in the new collections?

Scala Standard Library
81

I started to wonder if one of forall and exists should be removed.

82

I think they should both stay. While one could be used to replace the other in terms of functionality, clarity of the code will sometimes suffer quite a bit.

4 Likes
84

How about add an indexed function,which return an Traversable[Int,T]? ,means return an index first of zipWithIndex?

85

You can emulate such indexed with zipWithIndex.map(_.swap)

zipWithIndex is actually intuitive. I think it’s sufficient for indexing purposes.

86 
def iForeach(f: (A, Int) => Unit, count: Int = 0): Unit
def iMap[B](f: (A, Int) => B, count: Int = 0): Seq[B]
def iFlatMap[B](f: (A, Int) => Seq[B], count: Int = 0): Seq[B]

don’t like names but this is great idea. There is lot of places where .zipWithIndex kills performance.

i propose rather something like:

def mapWithIndex[E](f:(T,Int) => E):Seq[E]
def foreachWithIndex[E](f:(T,Int) => E):Seq[E]
//flatMap seams to be to specific?
2 Likes
87

I started to wonder if one of forall and exists should be removed.

clarification:

seq.forall(pred(_)) == !seq.exists(!pred(_))

for any pred