Swift Repl: How to Import, Load, Evaluate, or Require a .Swift File

Howto load SwiftPM project + its dependencies in Swift repl

These are the steps to follow for a solution using Swift 4.

Create a folder, let's say "TestSPMLibrary":

$ mkdir TestSPMLibrary
$ cd TestSPMLibrary

Create a library package:

$ swift package init --type library

In the "Package.swift" file, add the ".dynamic" library type.

You can also add a dependency such as Alamofire (you need to also add it to the target).

My "Package.swift" example:

// swift-tools-version:4.0

import PackageDescription

let package = Package(
    name: "TestSPMLibrary",
    products: [
        .library(
            name: "TestSPMLibrary",
            type: .dynamic,
            targets: ["TestSPMLibrary"]),
    ],
    dependencies: [
        .package(url: "https://github.com/Alamofire/Alamofire.git", from: "4.0.0"),
    ],
    targets: [
        .target(
            name: "TestSPMLibrary",
            dependencies: ["Alamofire"]),
        .testTarget(
            name: "TestSPMLibraryTests",
            dependencies: ["TestSPMLibrary"]),
    ]
)

In this library the code you want to interface with has to be declared public (and objects need a public initializer).

My "TestSPMLibrary.swift" example:

public struct Blah {
    public init() {}
    public var text = "Hello, World!"
}

Build the library:

$ swift build

Launch the REPL with swift -I .build/debug -L .build/debug -l and add the library name. In my case:

$ swift -I .build/debug -L .build/debug -lTestSPMLibrary

In the REPL you can now import your library (and its dependencies):

import TestSPMLibrary
import Alamofire

let x = Blah()
print(x.text)

Starting Swift REPL for iOS vs OSX

One way to do this is to create an iOS/OS X project and set a break point to interrupt the flow. Then, enter repl into the lldb console and enjoy.

For more on this one, watch WWDC 2014 session 409 - Introduction to LLDB and the Swift REPL.

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