Const-correctness and uniqueness. Again.

[Jakob Ovrum via Digitalmars-d]

On Monday, 9 February 2015 at 10:56:31 UTC, Dicebot wrote:
> Consider this trivial snippet:
>
> ```D
> import std.array : join;
>
> void main()
> {
> 	auto s = join([ "aaa", "bbb", "ccc" ]);
> 	pragma(msg, typeof(s));
> }
> ```
>
> It outputs "string" which stands for immutable buffer.

The following works as well:
---
void main()
{
	import std.array : join;
	import std.stdio : writeln;

	char[] s = join(["foo", "bar"]);
	writeln(s); //foobar
}
---

std.array.join is strongly pure (with appropriate template 
arguments), so its return value is implicitly convertible to 
immutable.