Just where has this language gone wrong?

[q66]

On Thursday, 19 July 2012 at 14:33:49 UTC, q66 wrote:
> On Thursday, 19 July 2012 at 14:31:41 UTC, Petr Janda wrote:
>>> Array gets sorted, then doubles are removed (uniq) and then 
>>> everything is converted to a string (map).
>>>
>>> Everything was recently introduced around 2.059.
>>
>> Ok, but what is map!(). What's the point of the exclamation 
>> mark, is it a template specialization?
>
> stuff after ! specifies template arguments, in this case a 
> predicate; "map" is a standard function in many languages; what 
> it does basically is to go over an iterable object, apply the 
> predicate function given in the template argument to each 
> element and returns a new iterable containing the results of 
> the predicate call on each element.

for example, auto x = [ 5, 10, 15, 20 ]; assert(map!(x => x + 
1)(x) == [ 6, 11, 16, 21 ])