[minxomat]

In modern contexts (outside of compilers): policy evaluation, see e.g. OPA's ReGo which uses Datalog enhanced with structured data support.

[nerdponx]

Would you want to use a Prolog/Datalog for things like authorizing users in a RBAC system? I give the engine a bunch of rules and properties of things, and the engine figures out whether or not the user is authorized to perform some specific action.

[minxomat]

That's exactly what OPA does.