Is there a builtin function to map a single argument to many kotlinlang #announcements

Channels

lincheck

kobweb

koalaql

kotlin-multiplatform-contest

osgi

brikk

revolver

tricity-kotlin-user-group

cincinnati-user-group

prozis-android-backup

refactoring-to-kotlin

russian-kotlinasfirst

androidgithubprojects

navigation-architecture-component

stayhungrystayfoolish

practical-functional-programming

tensorflow

swagger-gradle-codegen

kotlinultimatechallenge

competitive-programming

skia-wasm-interop-temp

java-to-kotlin-refactoring

event21-community-content

myndocs-oauth2-server

jvm-ir-backend-feedback

Title

Nezteb

04/23/2019, 7:31 PM

Is there a builtin function to map a single argument to many functions that take that same argument? i.e.

val myArg = 1
val myFuncs = listOf(::addOne, ::addTwo, ::addThree)

myArg.someCoolMapFunctions(myFuncs)

There’s a stack overflow answer for Haskell to define this function yourself, but I don’t know what the equivalent Kotlin code would be https://stackoverflow.com/a/47501940/7682196

streetsofboston

04/23/2019, 7:32 PM

I don’t think Kotlin has this. What would the return type of

someCoolMapFunctions

be?

Nezteb

04/23/2019, 7:33 PM

ListType<myArg>

I would think

streetsofboston

04/23/2019, 7:33 PM

you mean

List<Int>

? or

List<() -> Int>

Nezteb

04/23/2019, 7:34 PM

List<Int>

in this case

what i’m doing for now is:

val listOfOutputs = listOf<Int>()
for(func in myFuncs) {
    listOfOutputs += func(myArg)
}

streetsofboston

04/23/2019, 7:36 PM

fun Int.someCoolMapFunctions(list: List<(Int)->Int>) : List<Int> = list.map { it(this) }

Or if you want to return a

List<() -> Int>

(a list of deferred results instead of a list of results):

fun Int.someCoolMapFunctions(list: List<(Int) -> Int>) : List<() -> Int> = list.map { { it(this) } }

Ruckus

04/23/2019, 7:44 PM

I don't see why you need it.

val outputs = myFuncs.map { it(myArg) }

is pretty concise.

👍 1

Nezteb

04/23/2019, 7:46 PM

Ohhhhhhhh. Neat! I didn’t realize you could do that with the regular

map

. Thanks!

👍 2

2 Views

#announcements Join Slack