See [this thread](https://forum.nim-lang.org/t/6250). I think it would not be hard to modify the embedded inline parser in strformat to allow internal `:`, and this has come up often enough that it might be a good first PR...
- conditional expressions don't work in a formatted string HJarausch
- conditional expressions don't work in a formatted string jrfondren
- conditional expressions don't work in a formatted strin... cblake
- conditional expressions don't work in a formatted string xigoi
