Nim feedback by al6x

[mratsim]

I expect this will be detected at compile-time once we have the Z3 theorem 
prover:
    
    
    type
      DocKind = enum
        text,
        todo
      
      Doc = object
        case kind: DocKind
        of text:
          text: string
        of todo:
          todo: string
    
    let doc = Doc(kind: text, text: "some doc")
    echo doc.todo#compiles, throws exception
    
    
    Run

See 
[https://nim-lang.org/docs/drnim.html](https://nim-lang.org/docs/drnim.html) 
This is similar to eliding array bounds check and probably a low-hanging fruit 
to experiment with a prover integrated in a compiler.