Simplified if-else

IfElse.kt

infix fun <T>Boolean.then(action : () -> T): T? {
    return if (this)
        action.invoke()
    else null
}

infix fun <T>T?.elze(action: () -> T): T {
    return if (this == null)
        action.invoke()
    else this
}

IfElseTest.kt

class IfElseTest {

    @Test
    fun testIf() {
        val condition = true
        val output = condition then { 1 + 1 }
        assertEquals(2, output)
    }

    @Test
    fun testIfElze() {
        val condition = true
        val output = condition then { 1 + 1 } elze { 2 + 2 }
        assertEquals(output, 2)
    }

    @Test
    fun testIfElzeInt() {
        val condition = false
        val output = condition then { 1 + 1 } elze { 2 + 2 }
        assertEquals(output, 4)
    }

    @Test
    fun testIfElzeString() {
        val condition = true
        val output = condition then { "Condition is true" } elze { "Condition is false" }
        assertEquals(output, "Condition is true")
    }

    @Test
    fun testIfElzeStringFalse() {
        val condition = false
        val output = condition then { "Condition is true" } elze { "Condition is false" }
        assertEquals(output, "Condition is false")
    }

    @Test
    fun testIfElzeObject() {
        val condition = true
        val output = condition then { TestIfElze(10) } elze { TestIfElze(100) }
        assertEquals(output.integer, 10)
    }

    @Test
    fun testIfElzeObjectFalse() {
        val condition = false
        val output = condition then { TestIfElze(10) } elze { TestIfElze(100) }
        assertEquals(output.integer, 100)
    }

    class TestIfElze(val integer: Int)
}

Nice one !

https://gist.github.com/ragdroid/a74bddc13a6e391aa966d7f43be0ea04#file-ifelse-kt-L2

I think if you added the inline keyword, it would give you more options, like you wouldn't be afraid of extra allocations, so no leaks could happen, also the user of your code could return (in some cases) or do somethings like that.