Hi, I’m starting with Kotlin and was wondering wha...

# arrow

[Roger Cyr]

Hi, I’m starting with Kotlin and was wondering what was the “go to” for dependency injection… I saw that Kotlin has classic “DI containers” but was wondering if Arrow provided a more FP solution. (Environmental effects à la ZIO, or a more classic approach à la ReaderT)

[raulraja]

Hi @Roger Cyr, Arrow used to have Reader but we found it mostly useless over time given Kotlin natively supports extension receivers and suspension.
For example suspend Foo.doStuff(): Unit is equivalent to ReaderT<IO, Foo, Unit> and can also be passed as value and has type of suspend Foo.() -> Unit . this also applies to other names like “Environmental Effects” which I think just means here the suspended effect has access to the scope of its receiver and this receiver can be passed in any call site as argument.

[raulraja]

Additionally those abstractions rewrap functions which means double boxing for the most part, this is also a reason why we tossed them in Arrow as general abstractions

[raulraja]

I have some old examples of using receivers for DI here in case it helps. https://gist.github.com/raulraja/97e2d5bf60e9d96680cf1fddcc90ee67 .

[Roger Cyr]

Wow, thank you! This is going to help me a lot 🙂