Consider computation with the integers $\mathbb{Q}$. The traditional theory of recursive functions on $\mathbb{N}$ applies to $\mathbb{Q}$ by the identification of $\frac{a}{b} \in \mathbb{Q}$ with $2^{a}3^{b} \in \mathbb{N}$. Similarly, if I have any similar unnamed structure I can proceed likewise, as follows:

First, note that in this process of "Gödel numbering" a given object may have more than one representative Gödel number in $\mathbb{N}$. However the set of valid Gödel numbers is primitive recursive and there is a primitive recursive equivalence relation that determines whether two numbers represent the same object.

This leads to the following category $\textsf{PRA}$: The objects of $\textsf{PRA}$ objects are pairs $(A, \sim _{A})$ where $A \subseteq \mathbb{N}$ is a primitive recursive set and $\sim _{A} \subseteq A \times A$ is a primitive recursive equivalence relation. The morphisms of $\textsf{PRA}$ are are functions $f: (A, \sim _A) \rightarrow (B, \sim _B)$ induced by primitive recursive functions $F: \mathbb{N} \rightarrow \mathbb{N}$ such that $x \sim _{A} y \Rightarrow F(x) \sim _{B} F(y)$.

This is all rather rudimentary and seems like the correct definition (to me) of a Gödel numbering and leads naturally to the category just described. However I have never seen this category described or studied. Is this category simply

- Uninteresting, or perhaps
- Unimportant?

Any references would be appreciated. [See comment below.]