> My issue is that the 'reinitialise_with' function is called in a
> function 'phi' which is used in the following way:
>
> let message_event = React.E.map phi to_be_parsed_event.

Cannot really make sense out of your snippets of code. However this
phi functions seems to invoke a primitive event sending function and
that's explicitely prohibited by the documentation. Primitive event
sending/signal setting functions cannot be invoked as side effects
inside update cycles (see doc of E.create/S.create).

Not sure what you are trying to achieve but I suspect fixed point
combinators (E.fix/S.fix) may help you to solve your problem.

Best,

Daniel