[Haskell-cafe] newtype is superfluous
Benjamin.Rudiak-Gould at cl.cam.ac.uk
Sat Oct 15 09:07:21 EDT 2005
Wolfgang Jeltsch wrote:
> This is not true. With newtype, A _|_ is _|_, with data, A _|_ is not _|_.
It's probably more helpful to explain this in terms of a program that
exhibits different behavior in the two cases:
case error "data" of A x -> "newtype"
> But as far as I know, the above newtype declaration is equivalent to this:
> data A = A !Int
case A (error "data!") of A x -> "data or newtype"
More information about the Haskell-Cafe