compound context seq fn: inherit

        inherit[parent-type, op] input-seq
        inherit the given operator from the given parent-type
        We also try our best to maintain the "structure" of input-seq

        -- learn the parent types for an old cat named trudy:
        parent-type |trudy> => |cat>
        parent-type |cat> => |feline>
        parent-type |feline> => |mammal>
        parent-type |mammal> => |animal>

        -- learn some features from parent types:
        has-fur |animal> => |yes>
        has-teeth |animal> => |yes>
        has-pointy-ears |feline> => |yes>

        -- Trudy is an old cat, so has no teeth left:
        has-teeth |trudy> => |no>

        -- now, we can ask some questions:
        -- does trudy have pointy ears? Which we expect to inherit from feline
        inherit[parent-type, has-pointy-ears] |trudy>

        -- does trudy have fur? Which we expect to inherit from animal
        inherit[parent-type, has-fur] |trudy>

        -- does trudy have teeth? Which we inherit from animal, but is over-ridden by trudy:
        inherit[parent-type, has-teeth] |trudy>

        -- now, learn some info about a dog called rex:
        parent-type |rex> => |dog>
        parent-type |dog> => |canine>
        parent-type |canine> => |mammal>

        -- we already know the parent type of mammal is an animal

        -- do trudy and rex have teeth?
        inherit[parent-type, has-teeth] (|trudy> + |rex>)
            |no> + |yes>

    see also: