How to pass arguments to anonymous lambda function in Kotlin?

Question

I'd like to write an anonymous lambda function in Kotlin, but it looks like it doesn't take the argument passed to it. (It is not passed at all, since the IDE hints that "variable 'name' is never used".)

Code:

var name = "Tobias Boon"
println("reverse=" + fun(name: String): String {
    var t: String = ""
    for(i in name.indices.last downTo 1) {
        t += text.subSequence(i - 1, i)
    }
    return t
})

Currently prints: reverse=(kotlin.String) -> kotlin.String

You arent passing any argument to the function. You are defining a function, and not calling it. — marstran
– marstran, Commented Feb 13, 2017 at 12:13
I've read it. What's the problem then? What is your expected output? — marstran
– marstran, Commented Feb 13, 2017 at 12:16
I'd like to know how to pass that argument to the lambda... The desired input would be like this would produce println(name.reversed()) — Gergely Lukacsy
– Gergely Lukacsy, Commented Feb 13, 2017 at 12:19

Ingo Kegel · Accepted Answer · 2017-02-13 12:18:21Z

5

You never call the function with the parameter, it should be

val name = "Tobias Boon"
println("reverse=" + fun(name: String) : String {
   ...
      return t
}(name))

Btw, your particular example is already implemented in the standard library:

println(name.reversed())

answered Feb 13, 2017 at 12:18

Ingo Kegel

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2 Comments

Gergely Lukacsy Over a year ago

Thanks, that was I looking for! "name.reversed()" are you trolling me with this? :)

Gergely Lukacsy Over a year ago

I know. My intention with this code was to learn about lambdas, not to reverse strings.

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