Re: Array permutations

[Elmar via Digitalmars-d-learn]

I also should discourage its current form with large 
`tupleSize`s. The computation is in O(exp(values.length)). 
Instead of `~=` I would suggest an `std.array.appender` of arrays 
instead of an 2D-array for the `choices`, if the `choices` become 
large. Most efficient is a preallocated array capacity. In that 
case `~=` has very low overhead.