There are various programming environments where source code is not structured as big sequential files, but as sets of individual methods, Smalltalk with roots

There are various programming environments where source code is not structured as big sequential files, but as sets of individual methods, Smalltalk with roots on Alto being one of them (other such environments are various "4GL database systems"). While ST80 has standard textual source code format, it's not something you want to write by hand but essentially an semi-convenient serialization format (with slightly hackish implementation).