PToJSVal Int about jsaddle

[hamishmack]

This would be possible to add (PFromJSVal would not be so easy).

Currently JSVal is:

type JSValueRef = Int64
newtype JSVal = JSVal JSValueRef

We could change it to something like:

data JSValueRef =
      JSValueRef Int64
    | JSValueRefInt Int
    | JSValueRefDouble Double
    | JSValueRefText Text
    ...
newtype JSVal = JSVal JSValueRef

Do you think this would be useful? I am a little reluctant because adds quite a bit of complexity.

If we do add these, I am not sure if including JSValText is a good idea because using toJSVal will only send the Text once, but pToJSVal would send the Text each time the JSVal was used.