Is there a proposal for ignoring receiver or context receiver for lambdas when passing method refere...

# language-proposals

[simon.vergauwen]

Is there a proposal for ignoring receiver or context receiver for lambdas when passing method references? Similar to how you can pass a non-suspend method reference to a suspend lambda?

Untitled.cpp

[hfhbd]

How should it work if you access the context in example?

[Joffrey]

@hfhbd the context is not provided by the block lambda in example(), it is expected by the lambda. So example() is actually supposed to create it and pass it to the lambda, not the other way around.

[Joffrey]

I think the question is about allowing example(::one) instead of forcing example { one() } if one doesn't use the context.

[hfhbd]

yeah, but what should happen if you want to execute block inside example without a context provided?

fun <A> example(block: context(Fragment, View) () -> A): A { block(); TODO() }

Checking if the context is actually used could only work inside the module. Otherwise, a new version of the lib actually using the context would break the public api.

[Joffrey]

I don't understand your question. `example`'s definition guarantees that block will be given a context (if called). So example has to provide one when it calls block(). That is irrelevant to whether callers of example pass a lambda that actually uses it

[Joffrey]

Basically it is already allowed to pass a lambda that doesn't use the context:

example { one() }

This could be simplified to example(::one) but the compiler is a bit too strict about the function signature to realize that it's ok.

[Joffrey]

There is no need to infer anything or detect any usage, by the way. It's just a matter of deciding that a function type without a context is sort of a subtype of the same function type but with context. Just like we do when deciding that a function without suspend keyword is kind of a subtype of the same function type with a suspend keyword.

[hfhbd]

Ah, sorry I was confused. You are absolutely right, the context is not part of the example function but of the parameter. https://pl.kotl.in/jIDDXFwHM

[elizarov]

KT-57165 Consider context conversion for callable references

[simon.vergauwen]

Great, thank you @elizarov 🙏