Documentation

derive derives an incomplete instance for JSTuple, as well as completing other classes.

you write the newtype explictly, and derive does the rest.

 newtype JSX o = JSX JSObject

and then the start of the JSTuple instance, and the rest gets filled in

 derive [d| instance (SunroofArgument o) => JSTuple (JSX o) where
                type Internals (JSX o) = (JSString,JSNumber)
        |]

generates

 instance (SunroofArgument o) => Show (JSX o) where
    show (JSX o) = show o

 instance (SunroofArgument o) => Sunroof (JSX o) where
    unbox (JSX o) = unbox o
    box o = JSX (box o)

 instance (SunroofArgument o) => IfB (JSX o) where
    ifB = jsIfB

 type instance BooleanOf (JSX o) = JSBool

 instance (SunroofArgument o) => JSTuple (JSX o) where
    type instance Internals (JSX o) = (JSString, JSNumber)
    match o = (o ! attr "f1", o ! attr "f2")
    tuple (v1,v2) = do
        o <- new "Object" ()
        o # attr "f1" := v1
        o # attr "f2" := v2
        return (JSX o)