if not syntax

[hrrrrustic]

Since not keyword was introduced, it would be nice to be allowed to write like this

if not (something.IsValid)

instead of

if(!something.IsValid)

Yep, new version is a little bit longer, but it looks more readable and obvious
Also, if there are more than 1 conditions in brackets, it will be

if not (something1 op1 something2 op2 something3)

instead of

if (!(something1 op1 something2 op2 something3))

(yeah, it's possible to use de morgan's laws here, but it doesn't matter)

[canton7]

if not is basically the same as Ruby's unless. I'm sure there was a proposal for that, but it's really hard to search for....

The general consensus is that unless is more confusing than not when applied with multiple conditions (sometimes it works, but most of the time it takes some effort to parse), and is pointless when combined with else.

[PathogenDavid]

Yup, here's some of them: #157 dotnet/roslyn#7927

[Unknown6656]

_{'twas a joke, I couldn't help it ;)}
^{I know it has nothing to do with the proposal}