Sequences

SQL sequences are counters with concurrency control, often used to assign unique IDs. Ur/Web supports them via a simple interface. The only way to create a sequence is with the $\mathsf{sequence}$ declaration form.

$$\begin{array}{l} \mathsf{type} \; \mathsf{sql\_sequence} \\ ... ...thsf{int} \to \mathsf{transaction} \; \mathsf{unit} \end{array}$$