hi dears kotliners my issue of the day how can i have a high

Question

hi dears kotliners my issue of the day how can i have a higher order function that takes a vararg something like ``` fun foo vararg args Any gt Unit = ```

Shawn · Answer

`vararg` isn t yet supported on lambda parameters you ll have to use an anonymous `fun`

Shawn · Answer

as for mandating that as a parameter type I think `Array lt Any gt ` might technically be what it is under the hood but I doubt the compiler considers the signatures compatible

Nicholas Bilyk · Answer

Shawn is correct it would be KFunction1 lt Array lt out Any gt Unit gt under the hood

Nicholas Bilyk · Answer

``` fun vArgFunc vararg t String println All $ t joinToString fun t val z KFunction1 lt Array lt out String gt Unit gt = vArgFunc z arrayOf one two three ```

tseisel · Answer

As a workaround you can use the following signature ```fun foo f Array lt out Any gt gt Unit ``` which is equivalent and then simulate the vararg parameters with `arrayOf `

nfrankel · Answer

thanks guys for your super quick answer the array trick doesn t in my case as i want to genericize the following code ``` var sort2 = fun frequencies Map lt String Int gt = frequencies map it key to it value sortedByDescending it second fun profile f Map lt String Int gt gt List lt Pair lt String Int gt gt Map lt String Int gt gt List lt Pair lt String Int gt gt val profilewrapper = fun arg Map lt String Int gt List lt Pair lt String Int gt gt val start = System currentTimeMillis val result = f invoke arg val elapsed = start System currentTimeMillis print $ f toString took $elapsed secs return result return profilewrapper fun main sort2 = profile sort2 ``` so that `profile ` accepts a function that takes a `vararg` and return `Any`

Nicholas Bilyk · Answer

ah I see You ll need profile1 profile2 profile3 etc for the number of arguments you ll want to parameterize

Nicholas Bilyk · Answer

``` fun lt P1 R gt profile1 f P1 gt R P1 gt R fun lt P1 P2 R gt profile2 f P1 P2 gt R P1 P2 gt R ```

nfrankel · Answer

i thought about that < Nicholas Bilyk> but i d be happy to have the vararg stuff if i can though from your answer it seems it s not possible

Nicholas Bilyk · Answer

nope vararg is just sugar around accepting an array parameter You re thinking of something like ecmascript s arguments array which Kotlin doesn t support

nfrankel · Answer

many thanks for your help

Nicholas Bilyk · Answer

np slightly smiling face

Nicholas Bilyk · Answer

what if you changed it instead of profile p1 p2 to profile sort2 frequencies

Nicholas Bilyk · Answer

``` var sort2 = fun frequencies Map lt String Int gt = frequencies map it key to it value sortedByDescending it second inline fun lt R gt profile inner gt R R val start = System currentTimeMillis val result = inner val elapsed = start System currentTimeMillis print took $elapsed millisecs return result fun main args Array lt String gt val sorted = profile sort2 mapOf ```

nfrankel · Answer

thinking face it s not a real project so my constraint is to be able to replace the `sort2` variable with one wrapped by `profile ` otherwise yes good point