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

[Paul Backus]

On Sunday, 2 June 2019 at 16:39:57 UTC, Rnd wrote:
>
> 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.

It's possible, but I believe the version that takes the function 
as a template argument is easier for the compiler to optimize, so 
doing it that way is a better choice for the standard library.

Reducing complexity for first-time learners is a noble goal, but 
templates are used so pervasively in D that there's really no 
sense in trying to avoid them. If you'd like to learn more about 
D's templates, Philippe Sigaud has written an excellent tutorial:

https://github.com/PhilippeSigaud/D-templates-tutorial/blob/master/D-templates-tutorial.md