Spec#, nullables and more

[Walter Bright]

bearophile wrote:
> From that tutorial is looks well though-out, in general (but it's not
> complete yet). I suggest to take a look at how Spec# implements design by
> contract (ignoring the fact it enforces those contracts statically), because
> this may give good insights about how to improve D DbC.

 From what I recall of Eiffel, a considerably older language (1985), Spec#'s DbC 
design is almost a direct copy.