for your convenience, the correct link:
https://lukepalmer.wordpress.com/2010/01/24/haskell-antipattern-existential-typeclass/
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Thanks everyone, I very much appreciate your help, and I think it did help.
I've spent the last few days implementing a substantial chunk of my system
using each of two different techniques. I've ended up going with and ADT
containing functions closed over the 'thing'. This seems to be the conse
On 29/01/2013, at 12:43 PM, Bob Hutchison wrote:
>
> The immediate problem is mapping an input to the system, some json message
> containing a reference to the 'thing' (like a key of some kind). I have to
> take that reference and find the thing and operate on it. All operations are
> easily
> Today I thought it was about time to simplify how new 'things' of a certain
> kind are added to the system. These things are some a cross between an event
> and an assertion of a fact in a rule based system. There are many different
> kinds of these things. I already have more than a dozen com
On Mon, Jan 28, 2013 at 5:43 PM, Bob Hutchison wrote:
>
> Now, this is how I got caught: it seems to be impossible to have
> collections of things with a common type class if they have different
> types. How is it that I've written that many lines of code in Haskell and
> I'm just noticing this no
If I understand your message well enough, I think you are looking for
GHC's `ExistentialQuantification` extension. Building heterogeneous
collections is a common example of what existential types are useful
for. Take a look at this wiki page [1]; there is an example of how to
accomplish this there,
Hi,
I'm relatively new to Haskell, and consider myself to be towards the beginner
side of the scale. Nevertheless, I've got this Haskell program I've been
working on that's sitting around 11k lines right now. The pattern has been to
let it grow to then knock it back by 'refactoring' or whatever