This paper describes experiences from implementing key parts of a compiler for Modelica, an object-oriented language supporting declarative modeling and simulation of complex physical systems. Our implementation uses the attribute-grammar based tool JastAdd. In particular, we discuss the implementation of Modelica name analysis which is highly context-dependent, type analysis which is based on structural subtyping, and flattening which is a fundamental part of the Modelica compilation process.of so called modifications, Modelica. Key words: Modelica, JastAdd, compiler construction, reference attributed grammars