Evaluate flow control

[iusildra]

Allows to evaluate (and eventually pre-evaluate) flow control at runtime. For instance

case class Test(i: Int)
def test(t: Test) = s"test ${t.i}"

if (true) 1 else 2                    // res0: Int = 1
(if (true) Test(1) else Test(2)).i    // res1: Int = 1
(if (true) Test(1) else 2).i          // res2: Int = 1 thanks to pre-evaluation
test(if(true) Test(1) else 1)         // res3: String = "test 1"
(if (m()) Test(1) else 2).i          // fails because the `if` cannot be pre-evaluated

[adpi2]

Since this is not an extractor (it returns a Boolean), it should not be called unapply.