Type Pattern-Matching for Existential Types

[Ashley Yakeley]

At 2001-01-30 23:11, Johan Nordlander wrote:

>However, this whole idea gets forfeited if it's possible to look behind
>the abstraction barrier by pattern-matching on the representation. 

Isn't this information-hiding more appropriately achieved by hiding the 
constructor?

--
data IntOrChar = MkInt Int | MkChar Char
data Any = forall a. MkAny a
--

Surely simply hiding MkInt, MkChar and MkAny prevents peeking?

-- 
Ashley Yakeley, Seattle WA