val none : 'a option React.signalnone is S.const None.
val some : 'a React.signal -> 'a option React.signalsome s is S.map ~eq (fun v -> Some v) None, where eq uses s's equality function to test the Some v's equalities.
val value :
?eq:('a -> 'a -> bool) ->
default:[ `Init of 'a React.signal | `Always of 'a React.signal ] ->
'a option React.signal ->
'a React.signalvalue default s is s with only its Some v values. Whenever s is None, if default is `Always dv then the current value of dv is used instead. If default is `Init dv the current value of dv is only used if there's no value at creation time, otherwise the last Some v value of s is used.
value ~default s]t = v if [s]t = Some vvalue ~default:(`Always d) s]t = [d]t if [s]t = Nonevalue ~default:(`Init d) s]0 = [d]0 if [s]0 = Nonevalue ~default:(`Init d) s]t = [value ~default:(`Init d) s]t' if [s]t = None and t' is the greatest t' < t with [s]t' <> None or 0 if there is no such t'.