PToJSVal / ToJSVal Discrepancies with ghcjs-dom-jsffi

[johannesgerer]

There a many examples (most Callbacks and other things) of the following differences between:

jsaddle-dom version:

instance ToJSVal VoidCallback where toJSVal (VoidCallback (Callback r)) = toJSVal r

ghcjs-dom-jsffi version:

instance PToJSVal VoidCallback where pToJSVal (VoidCallback (Callback r)) = r

together with the missing in ghcjs-base

instance ToJsVal PToJSval where toJsVal = return . pToJsVal

this breaks code compatibility between GHC and GHCJS.

I am not sure which parts of the ecosystem should be fixed.

1. Should the above instance added to ghcjs-base?

2. Should one of ghcjs-dom-jsffi and jsaddle-dom be changed to make VoidCallback have the same instances in both?