the error is Error 20 35 Kotlin Type mismatch inferred type is Int gt Int but Int gt CharSequence was expected Should I explicitly convert that to a CharSequence Why thinking face

the definition of joinToString takes a lambda of type T gt CharSequence so yeah you have to return a String CharSequence ```myArray joinToString it 2 toString ```

Assuming your data type is `Array lt Int gt ` you could create something like this ``` fun Array lt Int gt joinToString separator CharSequence = prefix CharSequence = postfix CharSequence = limit Int = 1 truncated CharSequence = transform Int gt Int String return joinTo StringBuilder separator prefix postfix limit truncated n gt transform invoke n toString toString ``` Which would allow you to do `println myArray joinToString it 2 ` like you want

the error is Error 20 35 Kotlin Type mismatch inferred type kotlinlang #getting-started

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febs

01/16/2019, 9:49 PM

the error is "Error:(20, 35) Kotlin: Type mismatch: inferred type is (Int) -> Int but ((Int) -> CharSequence)? was expected". Should I explicitly convert that to a CharSequence? Why? 🤔

zpearce

01/16/2019, 9:54 PM

the definition of joinToString takes a lambda of type (T) -> CharSequence, so yeah, you have to return a String (CharSequence).

myArray.joinToString { (it*2).toString() }

✔️ 1

Tristan Caron

01/16/2019, 9:55 PM

Kotlin doesn't have implicit casts

febs

01/16/2019, 9:57 PM

so bad, that's pretty ugly.

println (mySecondArray.joinToString { (it*2).toString() } )

this works. But stating "joinToString" and then casting toString again doesn't look very kotlinish. Hope they'll fix that 😄

hudsonb

01/17/2019, 12:36 AM

It'd be pretty easy to create your own

joinToString

extension that works the way you describe

Assuming your data type is

Array<Int>

, you could create something like this:

fun Array<Int>.joinToString(separator: CharSequence = ", ", prefix: CharSequence = "", postfix: CharSequence = "", limit: Int = -1, truncated: CharSequence = "...", transform: ((Int) -> Int)): String {
    return joinTo(StringBuilder(), separator, prefix, postfix, limit, truncated) { n -> transform.invoke(n).toString() }.toString()
}

Which would allow you to do

println (myArray.joinToString { it*2 } )

like you want

aarjav

01/17/2019, 2:16 AM

^ at that point I'd argue it's better to do Any than Int specifically

hudsonb

01/17/2019, 2:32 AM

Sure

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