// *** before: ***
// the binary interface of the language changed from version to version, so
// every application carried its own copy of the standard library inside:
//   MyApp.app/Frameworks/libswiftCore.dylib
//   MyApp.app/Frameworks/libswiftFoundation.dylib
//   ... about a dozen files and several megabytes
// and a framework built by another compiler version simply did not link

// *** in version 5.0: ***
// the library moved into the system (iOS 12.2, macOS 10.14.4 and newer):
// the application became smaller, and a binary framework built by a
// different compiler keeps working
print("the standard library is taken from the system")

// module stability - the other half of the promise, the one that lets a
// binary framework be imported by a newer compiler - arrived in Swift 5.1