Hey there! Could someone point me to some docs explaining why `val (_) = Unpackable("Two")` does no...

# getting-started

[bitnot]

Hey there!

Could someone point me to some docs explaining why val (_) = Unpackable("Two") does not call component1 ?

[Milan Hruban]

https://kotlinlang.org/docs/reference/multi-declarations.html#underscore-for-unused-variables-since-11

[bitnot]

Thank you, @Milan Hruban, somehow I missed the The componentN() operator functions are not called for the components that are skipped in this way. part…

[Milan Hruban]

wouldn't make sense to call them, if we don't want the value 🙂

[bitnot]

Well, when it has a hidden effect of updating the state in for-comprehension, it’s just a bit surprising. 😄
Took me a bit to realize it was a Kotlin thing and not an Arrow thing.
https://github.com/bitnot/fpinkotlin/blob/practice/src/test/kotlin/chapter6/exercises/Exercise_6_11.kt#L89

[elizarov]

component1 with a side-effect 😱 My life will never be the same

[bitnot]

my bad, poor explanation. to be precise, component1 is overloaded to call monad extension function bind that calls suspendCoroutineUninterceptedOrReturn 😉

https://github.com/arrow-kt/arrow-core/blob/master/arrow-core-data/src/main/kotlin/arrow/typeclasses/MonadContinuations.kt#L31