non-lambda overloads for lambda-only things

[Berni44]

On Thursday, 15 April 2021 at 22:02:10 UTC, Steven Schveighoffer 
wrote:
>  Is this worth adding to Phobos?

YES! When I was a beginner, I did not know about templates 
parameters. I realized soon, that I sometimes need a `!` to make 
a function, like `std.conv : to` from Phobos work, but was quite 
often lost, when getting such "fun" error messages.
A hint toward a template parameter would have helped a lot.