A better way to write this function? (style question)

[Thomas Gann]

Thanks for all your replies, guys! I have done some further 
research in the meantime and I have found out that I am, in fact, 
an idiot. There is actually a standard library function that does 
exactly what I am trying to do! As it turns out, 
std.string.split():

1) It automatically discards empty tokens, so there is no need to 
filter it manually.
2) Its definition of whitespace includes spaces, tabs, and both 
types of newlines, so there is no need to convert newlines to 
spaces.

An equivalent, but much less verbose, form of the function 
becomes the following:

     input.toLower.split;

So I'm noticing a common theme here, though, which is that lots 
of operations on arrays is bad? Should I be using ranges pretty 
much everywhere, then? Or just in performance-critical areas of 
code where I want to avoid a lot of copying? Would that just 
leave plain vanilla dynamic arrays to the task of (relatively) 
permanent storage?