Scala-IO Core: Long Traversable

The LongTraversable trait is one of the most important objects in Scala IO. Input provides a uniform way of creating views on the data (as a string or byte array or LongTraversable of something like bytes.)

LongTraversable is a scala.collection.Traversable with some extra capabilities. A few of the salient points of LongTraversable are:

• It is a lazy/non-strict collection similar to Stream. In other words, you can perform operations like map, flatmap, filter, collect, etc... without accessing the resource
• Methods like slice and drop will (if possible for the resource) skip the dropped bytes without reading them
• Each usage of the LongTraversable will typically open and close the underlying resource.
• Has methods that one typically finds in Seq.  For example: zip, apply, containsSlice
• Has methods that take or return Longs instead of Ints like ldrop, lslice, ltake, lsize
• Has limitFold method that allows fold like behaviour with extra features like skip and early termination
• Can be converted to an AsyncLongTraversable which has methods that return Futures instead and won't block the program
• Can be converted to a Process object for advanced data processing pipelines

Example usage:

The limitFold method can be quite useful to process only a portion of the file if you don't know ahead of time what the indices of the portion are: