Information about the operating system application programming interfaces is stored in a known format in a known location. This information fully describes the APIs exposed by the operating system and is stored in API metadata files. A language compiler or interpreter uses this API information to build a natural and familiar representation of the native system API in the target language. The language compiler or interpreter can read the API information at compile time and/or runtime. The metadata is used to allow an application to refer to named elements in the API. Projections are built that use the metadata to map named elements in the API to named elements in the target language, and to define wrappers that marshal data of those elements between the target representation and the native operating system representation.