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 a 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.