An alternative code structure (version 6)

At this point, it's actually possible to write comprehensive code while using fewer modules in our code file. Let's keep the platform module, but move out what we had in the WebApp module in Using modules for code structure (version 5), thus eliminating that module. At the same time, we will adjust some names and definitions.

While we have fewer modules, we can improve our type-based code by introducing an interface file (src/Ch10/Ch10_PlatformCompany_V6.rei) to hold type information for the .re file (src/Ch10/Ch10_PlatformCompany_V6.re), as follows:

type webapp;
type pfcompany;

let appToString: webapp => string;

Next, we define the webapp and pfcompany types and adjust the appToString function accordingly (in src/Ch10/Ch10_PlatformCompany_V6.re), as follows:

/* Basic types and functions we need (see .rei file) */

type webapp...