Stream: ideas

Topic: dependency injection

nandi (Dec 26 2025 at 02:21):

I've been playing with the idea of platform agnostic libraries that allow you to inject platform things into. Logger is in our platform, Greeting is an external module.

StdoutWriter := [StdoutWriter].{
    write! = |_self, msg| Stdout.line!(msg)
}

# Wraps Logger
LoggerWriter := [LoggerWriter].{
    write! = |_self, msg| Logger.log!(msg)
}

    # Create writer instances
    stdout_writer : StdoutWriter
    stdout_writer = StdoutWriter

    logger_writer : LoggerWriter
    logger_writer = LoggerWriter

    # Example 1: Inject StdoutWriter into the Greeting module
    Stdout.line!("Example 1: Greeting module with StdoutWriter")
    Stdout.line!("---------------------------------------------")
    Greeting.greet!(stdout_writer, "Alice")
    Greeting.farewell!(stdout_writer, "Alice")
    Greeting.introduce!(stdout_writer, "Bob", "engineer")

    # Example 2: Inject LoggerWriter into the same module
    Stdout.line!("Example 2: Same module with LoggerWriter")
    Stdout.line!("-----------------------------------------")
    Greeting.greet!(logger_writer, "Charlie")
    Greeting.farewell!(logger_writer, "Charlie")
    Greeting.introduce!(logger_writer, "Diana", "designer")

Brendan Hansknecht (Dec 26 2025 at 04:41):

Yeah, things like this are exactly how to pass effects to generic libraries and packages

Brendan Hansknecht (Dec 26 2025 at 04:42):

Over time, I expect many platforms to implement the same interfaces (or packages to map them to the same interfaces).

That way, you can have tcp interface for example and use it for many platforms implement it. Then many generic libraries can use it to implement tons of different protocols.

nandi (Dec 26 2025 at 04:49):

Thats what my thinking was. Have a common convention based interface that is compatible across platforms. I feel like that's going to be deeply needed with the one platform per app constraint

Brendan Hansknecht (Dec 26 2025 at 05:00):

Yeah, for any effectful libraries, I think this will be fundamental

Brendan Hansknecht (Dec 26 2025 at 05:00):

It is now easier with static dispatch

Brendan Hansknecht (Dec 26 2025 at 05:00):

Cause you can use an object with static dispatch as an interface

Last updated: Jun 16 2026 at 16:19 UTC