% cat greetings.swift
public func sayHello(name: String) {
  print("Hello, " + name)
}

% cat input.swift
import Foundation

public func getInput() -> String {
  let stdin = NSFileHandle.fileHandleWithStandardInput()
  let data = stdin.availableData
  return NSString(data: data, encoding: NSUTF8StringEncoding) as! String
}

% cat main.swift
// This file must be named main.swift; the compiler won't allow top-level statements
// otherwise
import greetings

print("What is your name?")
let name = getInput()
sayHello(name)

# compiles greetings.swift and input.swift into a single "library" greetings.o
% swift -frontend -c -module-name greetings -sdk `xcrun --sdk macosx --show-sdk-path` -target x86_64-apple-macosx10.11 -g -enable-testing -emit-dependencies -emit-module -emit-module-path greetings.swiftmodule -enable-objc-interop -emit-objc-header -emit-objc-header-path greetings-Swift.h -c greetings.swift input.swift

# compiles main.swift into main.o
% swift -frontend -c -I . -c -primary-file main.swift -sdk `xcrun --sdk macosx --show-sdk-path` -target x86_64-apple-macosx10.11 -g -enable-testing -emit-dependencies  -enable-objc-interop main.swift

# links the final binary, automatically pulling in swift library dependencies
# note: the automatic swift library dependency system does NOT work if
# greetings.o is in a standard libgreetings.a AR archive and pulled in with -lgreetings
# (and it appears there are circular dependencies in these libraries so linking
# them manually is not fun)
% clang -isysroot `xcrun --sdk macosx --show-sdk-path` -mmacosx-version-min=10.11 -L/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift_static/macosx -Xlinker -force_load_swift_libs -lswiftRuntime -lc++ -framework Foundation -Xlinker -add_ast_path -Xlinker greetings.swiftmodule -o hello main.o greetings.o

% ./hello
What is your name?
Ben
Hello, Ben

% otool -L ./hello
./hello:
	/usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 120.1.0)
	/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation (compatibility version 300.0.0, current version 1252.0.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1225.1.1)
	/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 1253.0.0)
	/System/Library/Frameworks/CoreGraphics.framework/Versions/A/CoreGraphics (compatibility version 64.0.0, current version 600.0.0)
	/usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 228.0.0)