Inline onFocusChange kotlin

You simply forgot to call hasFocus:

setOnFocusChangeListener(View.OnFocusChangeListener { view, b -> hasFocus(b) })
                                                                 /\/\/\/\/\

This is a sweet and readable syntax:

yourEditText.setOnFocusChangeListener { _, hasFocus ->
    if (hasFocus)
        showSomething()
    else
        hideSomething()
}

Just to clarify, there isn't really a point in creating an inline method extension. This was my initial objective but I later realized that using:

editText.setOnFocusChangeListener { view, b -> doSomething(b) }

was possible, it's inline, it's pretty and no extra work is needed