  Category theory is famous for its innovative way of thinking of concepts by
their descriptions, in particular by establishing universal properties.
Concepts that can be characterized in a universal way receive a certain quality
seal, which makes them easily transferable across application domains. The
notion of partiality is however notoriously difficult to characterize in this
way, although the importance of it is certain, especially for computer science
where entire research areas, such as synthetic and axiomatic domain theory
revolve around notions of partiality. More recently, this issue resurfaced in
the context of (constructive) intensional type theory. Here, we provide a
generic categorical iteration-based notion of partiality, which is arguably the
most basic one. We show that the emerging free structures, which we dub
uniform-iteration algebras enjoy various desirable properties, in particular,
yield an equational lifting monad. We then study the impact of classicality
assumptions and choice principles on this monad, in particular, we establish a
suitable categorial formulation of the axiom of countable choice entailing that
the monad is an Elgot monad.
