$\forall$$T$:Type, $n$:$\mathbb{N}$, $h$, $f$:($T$$\rightarrow$($T$ + Top)). $f$\^{}$n$ o $h$   = primrec($n$;$h$;$\lambda$$i$,$g$. $f$ o $g$  ) $\in$ $T$$\rightarrow$($T$ + Top)