Issues with nested [%shared ...] expressions

[mfp]

I'm told nested expressions are meant to work, but ran into these:

let borken_maybe (x : int) s =
  S.map [%shared S.map [%shared ((+) ~%x)]] s

File "bug1.eliom", line 22, characters 54-55:
Error: Unbound value x

same with

let borken_maybe (x : int) s =
  S.map [%shared let x = ~%x in S.map [%shared ((+) ~%x)]] s

Furthermore, it seems nested [%shared] expressions are disallowed altogether:

let borken_maybe (x : int) s =
  S.map [%shared S.map [%shared ((+) 1)]] s

File "bug1.eliom", line 22, characters 38-55:
The syntax [%shared ...] can not be nested.

Both can be worked around by moving the inner expressions to a top-level binding, but it quickly becomes quite inconvenient when you're working with dynamism (signals of signals): imagine having to use a (named) top-level function to replace every lambda :-)

[mfp]

As it turns out, there's a better, much more convenient workaround:

let borken_maybe (x : int) s =
  let plus_x x = [%shared ((+) ~%x)] in
    S.map [%shared S.map (~%plus_x ~%x) ] s