Hi i ve got a good one for you smiley Can t find the right way to set the Type Parameter for an infix any ideas ``` class SomeHolder private val someMap = mutableMapOf lt String Any gt private infix fun T String from transformation Any gt T = transformation invoke someMap this fun SomeHolder test works but no return type assurance test from input gt when input is String gt input toFloatOrNull else gt null not working otherTest from lt Float gt input Any gt when input is String gt input toFloatOrNull else gt null not working lt Float gt yet another from input Any gt when input is String gt input toFloatOrNull else gt null not working yet another lt Float gt from input Any gt when input is String gt input toFloatOrNull else gt null not working arrrg from input Any gt when input is String gt input toFloatOrNull else gt null lt Float gt ```

class SomeHolder {

    private val someMap = mutableMapOf<String,Any()>


    private infix fun T String.from(transformation : (Any?)-> T?) =
        transformation.invoke(someMap[this])

    fun SomeHolder.test() {
        
          //works but no return type assurance
          "test" from {input ->
            when(input) {
                is String -> input.toFloatOrNull()
                else -> null
            }
        }

        //not working
        "otherTest" from<Float> { input : Any? ->
            when(input) {
                is String -> input.toFloatOrNull()
                else -> null
            }
        }
        
        //not working
        <Float> "yet another" from { input : Any? ->
            when(input) {
                is String -> input.toFloatOrNull()
                else -> null
            }
        }     
        
        //not working
        "yet another" <Float>from { input : Any? ->
            when(input) {
                is String -> input.toFloatOrNull()
                else -> null
            }
        }
        
        //not working
        "arrrg" from { input : Any? ->
            when(input) {
                is String -> input.toFloatOrNull()
                else -> null
            }
        }<Float>
    }

}

Andreas Sinz

03/06/2018, 1:09 PM

What do you mean with

no return type assurance

silas.schwarz

03/06/2018, 1:10 PM

by setting the type parameter at the method (see all not working statements) it want to enforce the return type of the transformation to be a specific type

<Float>

but i haven't found a way to set a TypeParameter in an inline function

i can define one

but can't use it

Andreas Sinz

03/06/2018, 1:11 PM

i don't think its possible define the Type parameter of an infix function right now

but you can still use it like a normal function which is only a single dot added

silas.schwarz

03/06/2018, 1:14 PM

yeah i know

i just wanted to point out and see if a) im doing it wrong or b) it is just not yet possible

if b) i would like to propose the my first variant from<Float>

😃

did i say if ? i meant to say when

Andreas Sinz

03/06/2018, 1:15 PM

and then you end up with

a +<MySuperCoolClass> b

silas.schwarz

03/06/2018, 1:16 PM

well not on operator fun that would look crazy

Andreas Sinz

03/06/2018, 1:18 PM

an operator is just a regular infix function too (with the added property of being an operator)

https://youtrack.jetbrains.com/issue/KT-21593

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