Am Samstag 13 Februar 2010 22:03:20 schrieb Felipe Lessa:
On Sat, Feb 13, 2010 at 03:29:55PM -0500, Rick Murphy wrote:
I understand from [1] that a distinguised type is defined as a type with only one non-bottom value and that value is in fact identical to the name of the type. [1] provides the unit type () as an example of a Haskell distinguished type.
Would it be accurate to say that an approach to creating distinguished types in Haskell is to create data types with a single constructor whose name is identical to the data type name?
Well, I don't have not even one milliOleg.
I must confess, I don't know how much type-fu a milliOleg denotes.
That said, I think he used "distinguished" to mean that it is a "curious" data type included in the language.
Yep, "distinguished" as in "special" (often plays a role akin to void in C/Java).
Maybe he also meant that, at least in Haskell, the type may receive special notation (you can't say 'data () = ()').
HTH,
-- Felipe.