A couple of extensions to `with` that would be worthwhile

[max haughton]

On Wednesday, 13 October 2021 at 11:13:32 UTC, Andrei 
Alexandrescu wrote:
> We have an awkward idiom in the dmd source code:
>
> https://github.com/dlang/dmd/search?q=extendedPathThen
> https://github.com/dlang/dmd/search?q=toWStringzThen
>
> [...]

We could also have a trailing with to allow  Haskell style blah 
where blah = xyz code.