I don't know what "slicing," "in-built tmaps" or "x-platform" are..
Slices are essentially portions of arrays or strings (although the syntax is slightly different with strings than it is with arrays).
Slices:
Local a:Int[] = [1,2,3,4,5] For Local i:Int = eachin a[2..] print i Next
One thing you can't currently do with slices (but according to Mark's worklog will be added at some point) is concatenate them.
TMap: One example of many.