is there any micro improvement to use explicit types in rela kotlinlang #announcements

is there any micro improvement to use explicit types in relation to compilation time? In Swift you can get faster compilation time if you set explicit types, I am not sure how Kotlin deals with it.

erluxman

09/19/2018, 9:52 AM

I think Its true in every programming language? Not 100% sure though

gildor

09/19/2018, 10:24 AM

In theory it should be faster, but I never saw any evidences that explicit type somehow helps with compilation time. I wouldn’t recommend to use this approach. Better to spend time on optimisation that really can help, such as modularisation of your project or even just profiling your build

pp.amorim

09/19/2018, 10:34 AM

Thank you. I am not having problems with the compile time, I am just curious.

in Swift, if you don't set the type of your array, the compiler gets super slow and sometimes crash

you can't do

let d = [foo, bar, fee]

with many items. The compiler never finishes the compilation. You need to do:

var d: [Int] = []; d += foo; d += bar; d += fee

😱 5

erluxman

09/19/2018, 11:39 AM

Really?

pp.amorim

09/19/2018, 12:38 PM

https://medium.com/@johnsundell/improving-swift-compile-times-ee1d52fb9bd

Read about Collection literals

String concatenation also suffer this problem, this is hilarious: https://stackoverflow.com/a/48916182/2430555 "Expression was too complex to be solved in reasonable time"

I did this once and the compiler running on a CI took 30 minutes to compile a single line. :trollface:

gildor

09/19/2018, 1:48 PM

Wow

It has to do with type inference. Each time you use the + operator, Swift has to search through all of the possible overloads for + and infer which version of + you are using

is this because of explicit imports are not required by default?

pp.amorim

09/19/2018, 1:57 PM

probably, this could be solved with caching...

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