--Handling of polymorphic types: 
-- testing that tyvars are instantiated to unknown

:set -XExistentialQuantification -XDeriveDataTypeable -XGeneralizedNewtypeDeriving
:l Test
let t = O (map Just [[1 :: Int,1],[2,2]])

:p t
:t _t1
seq _t1 ()
:p t
seq _t2 ()
:p t
:t _t4