Editing Inlining and Specialisation (section)

= What is an interface file? =

An interface file stores all information about a module which is needed by other modules.

The key to cross-module inlining and specialisation is making sure that we have the definitions of functions we want to inline at hand. Information is only passed between modules by interface files, therefore we must include the unfoldings of definitions in interface files if we want to inline them across modules.

The extension for interface files is <code>.hi</code>, you can see what's in an interface file by using the <code>--show-iface</code> flag.