Add 'role' data attribute. Note, that 'role' attribute is a part of reach ARIA API described here: http://www.w3.org/TR/wai-aria/ Among 'role', it defines lots of aria-* attributes

con id = fold (fn nm => fn t :: Type => fn acc => [nm] ~ acc => [nm = t] ++ acc) []

con idT = id [D = int, E = float]

val idV = fn x : $idT => x.E