pub fn derive_prefer_list(input: DeriveInput) -> Result<TokenStream>Expand description
Derive PreferList: adds the PrefersList marker trait and an IntoR impl
that converts to R by first calling IntoList::into_list, then into_sexp.
The type must also derive IntoList for this to compile. The generated
IntoR::Error is Infallible (list conversion is infallible for valid structs).