The solution may be as simple as importing std.array (or std.range) but we can't be sure without a short but complete code.
Solution was as simple as importing std.array. Thanks a lot again Ali.
Just for curiosity; why can't I use numArr.take(3);source\app.d(33): Error: no property 'take' for type 'MapResult!(unaryFun, FilterResult!(__lambda3, FilterResult!(__lambda2, char[][][])))'.
