From: arne@vajhoej.dk   
      
   On 11/15/2025 9:16 PM, Dan Cross wrote:   
   >> Also note the availability of the 'Valid attribute to make sure that what   
   >> is in the variable after the unsafe conversion is actually a valid value.   
   >   
   > Sum types make this trivial:   
   >   
   >      impl SomeType {   
   >          fn try_from(i: i32) -> Option {   
   >              // if valid, return `Some(whatever`),   
   >              // else return `None`.   
   >          }   
   >      }   
   (assuming Option in Rust is what it is in other languages)   
      
   Option and Ada Valid are somewhat different.   
      
   Option is a way for a function/method to either return   
   a value or return the fact that there is no value.   
      
   A much better way to do that than traditional   
   return null or -1 or whatever to indicate there   
   is no value.   
      
   Ada valid attribute is a runtime check on the result from   
   an unsafe conversion to see if it meets the constraints   
   of the data type.   
      
   Arne   
      
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