SWI-Prolog -- (>:<)/2

Availability:built-in

+Dict1 >:< +Dict2

This operator specifies a partial unification between Dict1 and Dict2. It is true when the tags match and the values associated with all common keys have been unified. The values associated to keys that do not appear in the other dict are ignored. Partial unification is symmetric. For example, given a list of dicts, find dicts that represent a point with X equal to zero:

    member(Dict, List),
    Dict >:< point{x:0, y:Y}.