[OT] - C++ exceptions are becoming more and more problematic

[__StarCanopy]

On Saturday, 26 February 2022 at 23:56:31 UTC, H. S. Teoh wrote:
> In theory, your own error return type would be a sum type of 
> all error returns of the functions you call plus your own error 
> codes. In practice, I honestly doubt if anyone would bother 
> doing this

I tried to help alleviate this pain by creating a template that 
pipes a given sequence of functions, consolidating all possible 
types into a new result type.
```d
// Very contrived example
//          int, Outcome!(int, IsNegativeError), Outcome!(int, 
IsOddError)
chain!(() => -1,                     isPositive, isEven)()
     .handle!(
         num => text(num, " is an even, positive integer"),
         (IsNegativeError err) => text(err.num, " is a negative 
integer"),
         (IsOddError err) => text(err.num, " is an odd integer")
     ) // Outcome!(int, IsNegativeError, IsOddError)
     .writeln; // -1 is a negative integer
```