Why is std.algorithm so complicated to use?

[Christophe Travert]

Jacob Carlborg , dans le message (digitalmars.D:171739), a écrit :
> On 2012-07-10 18:42, Daniel Murphy wrote:
>> "Jacob Carlborg" <doob at me.com> wrote in message
>> news:jthlpf$2pnb$1 at digitalmars.com...
>>>
>>> Can't "map" and "filter" return a random-access range if that's what they
>>> receive?
>>>
>> map can, and does.
> 
> It doesn't seem to:
> 
> auto a = [3, 4].map!(x => x);
> auto b = a.sort;
> 
> Result in one of the original errors I started this thread with.

here, map is random-access. But random access is not enough to call 
sort: you need to have assignable (well, swapable) elements in the 
range, if you want to be able to sort it. values accessed via a map are 
not always assignable, since they are the result of a function.

It seems the map resulting from (x => x) is not assignable. This is 
debatable, but since (x => x) is just a stupid function to test. 
Otherwise, you could try the folowing:

auto a = [3, 4].map!(ref int (ref int x) { return x; })();
a.sort;