Re: [Haskell-cafe] self-referential data

9 Aug 2008


      brian wrote:
...
On Sat, Aug 9, 2008 at 5:18 PM, Brent Yorgey  wrote:
...
The problem is that BString is not a type, it is a data constructor.
I know.
...
You could use M.Map BValue BValue, but of course that's probably not
what you want either.
Right. That wouldn't be according to spec either.
...
What's wrong with just using 'String' as the Map key?
It seems wrong. Yeah, it's just a String, but we're being all abstract
because that's better practice. It happens that when you parse
bencoded data, the length of the string is given. Maybe I want to
store that in BString, too.
But mainly I want to know how to think about it differently so that I
know what to do when it comes up again and actually matters.
What about using a type parameter:

data BValue bString = BString     bString
                     | BInteger    Integer
                     | BList       [BValue bString]
                     | BDictionary (Map bString (BValue bString))


Regards,
Maciej

Re: [Haskell-cafe] self-referential data

Maciej Podgurski