问defer()和defer{}之间的区别是什么

EN

fun wrapFunctionCall(callback: (Int) -> Int) {
   println(callback(3))
}

wrapFunctionCall(x: Int -> {
  x * x
})

// Most of the time parameter type can be infered, you can then let it go
wrapFunctionCall(x -> {
  x * x
})

// Can omit parameter, and let it be name `it` by default
wrapFunctionCall({
  it * it
})

// wrapFunctionCall accepts a lambda as last parameter, you can pull it outside the parentheses. And as this is the only parameter, you can also omit the parenthesis
wrapFunctionCall {
  it * it
}