From what I understand, this code

is equivalent to this one :

In the second case, it's a simple recursion, so far so good ... but when I look at the implementation of "forever" i can't wrap my head around :

forever a   = let a' = a *> a' in a'

How does this works ? How does this make an infinite loop ?

I understand that *> discard his right argument but it doesn't help me understand how forever implement an infinite loop ...