ulkb.util.unfoldr

unfoldr(f, x)

Right-unfolds x using unpacking function f.

Equivalent to:

def h(t):
   if f(t) is None:      # no more unpacking
      return [t]
   else:
      return [t[0]] + h(t[1])

Used to recover values which were right-folded. For example:

>>> f = (lambda t: t if isinstance(t, tuple) else None)
>>> it = unfold(f, (1, (2, (3, 4))))
>>> list(it)
[1, 2, 3, 4]