Straight from the documentation: "returns a new range" -- no
guarantee made about the relation of return type and parameter
type.
These functions return range objects to amortize the potential
cost of the operation, with a very small initial cost (a
reference to the input range), which is actually very useful in a
great many situations. They are all written as generics operating
on ranges as both input and output. For better or worse, this
has become the de facto D idiom. If you really do just want the
array out of it, import std.array and call the eponymous function:
example = example.filter!isLongEnough().array();
Voila. This iterates the full range and collects the results, as
expected. What *would* be nice would be to have "InPlace"
variations of these functions for use cases such as yours, in
order to re-use resources.
example.filterInPlace!isLongEnough();
Bam, done; assuming the input is a random access range (which a
basic array is, is it not?).
