| Regarding reusing constructor names across several datatypes: is it
| possible to qualify them with their enclosing datatype name, like
| Maybe.Nothing where there is a name conflict? Then I might reuse
| Nothing in my hypothetical data type, and it would be NEither.Nothing
| if conflicting with
| Suppose I want to extend this datatype to the one including
| possibility of neither Left or Right (i. e. None). Currently I have to
| use Maybe Either, so my options are:
|
| Just (Left a)
| Just (Right b)
| Nothing
|
| If I could extend the Either datatype I might have (syntax may be
|
David Menendez wrote:
The downside is that a function that might normally be typed Either A B
- C now will have the type:
(HTypeIndexed l,
HTypeProxied l,
HOccurs (Proxy (Left A)) l,
HOccurs (Proxy (Right B)) l) =
TIC l - C
But it will accept a TIC (HEither A B) and a TIC
On Fri, 29 Apr 2005, Simon Peyton-Jones wrote:
2. Use sub-typing, so that a value (Left x) is *both* in type Either
and in type NEither. This opens a very large and complicated design
space, as Ben mentioned.
I've been playing with this design space for a while and think there's at
least one
Philippa Cowderoy [EMAIL PROTECTED] wrote:
On Fri, 29 Apr 2005, Simon Peyton-Jones wrote:
2. Use sub-typing, so that a value (Left x) is *both* in type Either
and in type NEither. This opens a very large and complicated design
space, as Ben mentioned.
I've been playing with this design space
Hi,
Is it possible to have such a feature in the future versions of the
Haskell language?
For example, there is an Either datatype which is Left a| Right b.
Suppose I want to extend this datatype to the one including
possibility of neither Left or Right (i. e. None). Currently I have to
use
Benjamin Franksen writes:
On Thursday 28 April 2005 16:48, Dimitry Golubovsky wrote:
PS Or is there a similar feature in the language already?
Not one I know of.
The type-indexed co-products from Appendix C of the HList paper[1] are
along those lines, but probably not convenient enough for
