[TYPES] MSO logic and types

[Burak Emir]

I am looking for type systems for *programming languages* based on MSO 
logic.

Specifically, I am looking for slightly more powerful languages than 
queries on trees, as e.g. such that can type pattern matching and 
querying on graphs, or such that can type "higher-order" queries.

Has there been more work like Nils Klarlund and Michael I. 
Schwartzbach's Graph Types, POPL 93 ?

Thanks a lot.

Burak Emir