ReduceByKey for Collections

[scabug]

I think it would be nice to have a simple reduceByKey for some collections like this:

str.split("").map(l => (l, 1)).reduceByKey(_+_)

I know there is an easy implementation for reduceByKey as in
[http://stackoverflow.com/questions/15975384/scala-reducebykey-function-use-any-type-that-has-method]
but by adding such a function to collection, we can have a faster implementation for it.

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-9064?orig=1
Reporter: Muhammad-Ali A'rabi (angellandros)

[scabug]

Muhammad-Ali A'rabi (angellandros) said:
I am implementing a class for paired Traversable type, to add these functions to it.
Anyway, why I can't assign the bloody task to myself?

[scabug]

Muhammad-Ali A'rabi (angellandros) said:
I reimplemented the method, and it's damn fast. On a paired list with 20 entries and 6 different keys, it is 25% faster than Stack Overflow implementation (although, that only works with +), and 4.5x faster than bare-hand implementation of it using a bunch of scala maps and reduces:

pairedList.groupBy(_._1).map(l => (l._1, l._2.map(_._2).reduce(_+_)))

Take a look at this:
[http://ideone.com/dyrkYM]

[NthPortal]

fixed by the addition of groupMapReduce in 2.13