include

An include declaration can be used to include definitions from other .alfa files.

This is only required if when compiling an ALFA project, a root file is specified, as opposed to a directory. If a directory is specified, the ALFA compiler compiles all files in the directory and there is no need to use include.

If on the other hand, there is an usecase to only compile a subset of files, those can be grouped together using include.

include is a top level declaration, and is required to be at the beginning of a file before any other declarations.

include "commontypes.alfa"

Use of include is optional. Including the same file more than once or reaching the same file multiple times transitively has no side-effects as the ALFA compiler will read the file only once.