Convert double to long if lossless

[Per Nordlöw]

On Tuesday, 19 January 2021 at 21:04:51 UTC, kdevel wrote:
> And then? I mean: What do you want to do with the long what 
> could not
> be done with the double in the first place?

Motivated question.

We want to propagate to our system locally that a double received 
from a network communication actually is an integer and should be 
stored and treated as such in an algebraic type.