adamc@841: datatype t = datatype Basis.option
adamc@841: 
adamc@846: fun eq [a] (_ : eq a) =
adamc@846:     mkEq (fn x y =>
adamc@846:              case (x, y) of
adamc@846:                  (None, None) => True
adamc@846:                | (Some x, Some y) => x = y
adamc@846:                | _ => False)
adamc@846: 
adamc@944: fun isNone [a] x =
adamc@944:     case x of
adamc@944:         None => True
adamc@944:       | Some _ => False
adamc@944: 
adamc@841: fun isSome [a] x =
adamc@841:     case x of
adamc@841:         None => False
adamc@841:       | Some _ => True
adamc@844: 
adamc@844: fun mp [a] [b] f x =
adamc@844:     case x of
adamc@844:         None => None
adamc@844:       | Some y => Some (f y)
adamc@846: 
adamc@846: fun bind [a] [b] f x =
adamc@846:     case x of
adamc@846:         None => None
adamc@846:       | Some y => f y