  In the paper "Extensional PERs" by P. Freyd, P. Mulry, G. Rosolini and D.
Scott, a category $\mathcal{C}$ of "pointed complete extensional PERs" and
computable maps is introduced to provide an instance of an \emph{algebraically
compact category} relative to a restricted class of functors. Algebraic
compactness is a synthetic condition on a category which ensures solutions of
recursive equations involving endofunctors of the category. We extend that
result to include all internal functors on $\mathcal{C}$ when $\mathcal{C}$ is
viewed as a full internal category of the effective topos. This is done using
two general results: one about internal functors in general, and one about
internal functors in the effective topos.
