[Haskell] GADT: call for proper terminology

Niklas Broberg wrote:

Annotate the data type using a GADT: data MyData a where MyCon :: MyData a

The range of the data constructor MyCon is the entire type MyData a -- so the above data type is the regular algebraic data type, and can be written just as data MyData a = MyCon which, some say, makes the fact 'a' is phantom, and the overall intent clearer. One may hear phrases how generally awesome and indispensable GADT are; it is distressing to realize then that sometimes (often?) one is talking about regular algebraic data types, only in the `where' syntax. It helps to reduce confusion about the merits of various features and additions to Haskell if we use the term GADT exclusively for truly _generalized_ algebraic data types.