D equivalent to Rust or Scala's Optional and Result and best practice ?

[dangbinghoo via Digitalmars-d-learn]

hi,

It seems that now we have `Optional` and `Result` packages in 
Dub, are these enough or fully equal to Rust or Scala's 
error-handling and pattern-matching?

if these are enough for real-code, any best practice advice?

thanks!