There is the GSL by iMatix
<a href="https:&#x2F;&#x2F;github.com&#x2F;imatix&#x2F;gsl" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;imatix&#x2F;gsl</a>
(so closely associated with Pieter Hintjens of <a href="http:&#x2F;&#x2F;zeromq.org&#x2F;" rel="nofollow">http:&#x2F;&#x2F;zeromq.org&#x2F;</a>)