Array concat quiz

[Timon Gehr]

On 12/17/2011 02:43 AM, bearophile wrote:
> A small quiz. This Python2 code:
>
> m1 = [["A'", "B'"]]
> print m1
> m2 = m1 + [[]]
> print m2
>
>
> Prints:
>
> [["A'", "B'"]]
> [["A'", "B'"], []]
>
>
> What does this D2 program print?
>
> import std.stdio;
> void main() {
>      string[][] m1 = [["A'", "B'"]];
>      writeln(m1);
>      string[][] m2 = m1 ~ [[]];
>      writeln(m2);
> }
>
> Bye,
> bearophile

I do not think that this is very sensible (array-array appends are more 
natural than array-element appends, so disambiguation should go the 
other way). Is it documented anywhere or is it just an implementation 
artefact?