[Caml-list] Signals of signals in react

[Philippe Veber <philippe.veber@gmail.com>]

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Dear functional-reactive camlers,

In order to change the dependencies between signals dynamically, one can
use the switch function whose type is:

utop $ React.S.switch;;
- : ?eq:('a -> 'a -> bool) -> 'a React.signal -> 'a React.signal
React.event -> 'a React.signal = <fun>

However I often find myself wanting to write signals of signals, and I
wrote the following definition to cope with them:

val bind_s : 'a React.signal -> ('a -> 'b React.signal) -> 'b React.signal
let bind_s s f =
  let s' = S.map ~eq:( == ) f s in
  let init = S.value s'
  and changes = S.changes s' in
  S.switch init changes

So far it worked as I thought it would, but still I'm not really confident
this is a safe use of signals. Does anyone see a potential pitfall here?

Cheers,
  Philippe.

PS at least, there should be an eq optional attribute to [bind_s], and the
last line should be [S.switch ~eq init changes]

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