Study on hash associative arrays

[Ola Fosheim Grøstad" <ola.fosheim.grostad+dlang at gmail.com>]

On Thursday, 9 January 2014 at 10:48:22 UTC, bearophile wrote:
> Through Reddit I've found posts about hash-based associative 
> arrays:
>
> http://bannalia.blogspot.it/2013/10/implementation-of-c-unordered.html

I think the worry that a hash function should throw an exception 
is a bit over the top? Why would you do that?