It turns out it's quite hard to have @safe pure nothrow functions. Oh, and const.

[Timon Gehr via Digitalmars-d]

On 09/13/2014 07:48 PM, Kagamin wrote:
> On Saturday, 13 September 2014 at 16:51:09 UTC, Timon Gehr wrote:
>> s.bar((int* p){ ++*p; });
>
> Huh? inout is for functions, which don't modify their arguments.

With Jakob's code working, this would not be warranted. (But the 
situation needs to change in any case. The inout delegate semantics DMD 
2.066.0 implements cause type unsoundness as explained here: 
https://issues.dlang.org/show_bug.cgi?id=10850 .)

If inout should still guarantee non-modification in the future, then 
nested inout functions will need to introduce their own inout context 
(i.e. the inout qualifier of the nested function should be incompatible 
with the inout qualifier of the enclosing function.) I assume this is a 
major PITA to implement in DMD, and it also leads to growing pains that 
are hard to counter without enhancing the syntax, hence the current 
semantics.

In any case, why is it important that inout functions are guaranteed not 
to change their arguments, even if they are mutable and the mutation is 
from within a delegate that was passed to such functions for this purpose?