Why does the compiler (IntelliJ) not accept this `fold` lambda? error is `Kotlin: Type mismatch: inf...

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[Benoît Liessens]

Why does the compiler (IntelliJ) not accept this fold lambda?
error is Kotlin: Type mismatch: inferred type is Unit but Int was expected

fun <T, Int> Iterable<T>.sum(tx: (T) -> Int): Int {
    return map { tx(it) }
        .also { it -> println(it) }
        .fold(0 as Int) { acc, next -> acc + next }
}

[Dominaezzz]

typo <T, Int>

[Benoît Liessens]

Thanks

[Sam]

By declaring <T, Int> you have actually made a new generic parameter called Int which is not the same as (and is hiding) the real Int type. If you just drop that generic parameter from the signature, it should work.