What does ! Stand for in map! and filter! function calls?

[Rnd]

On Sunday, 2 June 2019 at 15:55:46 UTC, Paul Backus wrote:
> On Sunday, 2 June 2019 at 15:48:54 UTC, Rnd wrote:
>> I have recently started using Dlang, hence this basic 
>> question. Thanks for your insight.
>
> map and filter are templates in D, and !(...) is D's syntax for 
> passing arguments to templates:
>
> map!(x => x*x)([1, 2, 3, 4, 5])
>      ^         ^
>      |         |
>      |         +- This array is a normal function argument
>      |
>      +- This lambda is a template argument

Is it not possible in the language to have template map function 
also to called as map(x=>... ?

This will reduce complexity which will attract more people to 
this language.

Easy languages have great mass appeal as has been shown with Ruby 
and Python.