Re: [Haskell-beginners] Question about data structures

I gave this concrete example a couple of messages ago. Let's assume that instead of keeping for each cage the Operation and target number we pre-compute all the combinations of values that will satisfy the cage. For example, assume that in a 4x4 game, we have a cage that refers to cells C1 and C2 and that the cage requires those two cells to produce a value of 2 using division, Pre-computing the possibilities, we store [(1, 2), (2, 1), (2, 4), (4, 2)] in this cage. The cage points to the two cells it constrains, and each cell points to the cage that constrains it. When a cell (say C1) gets a value of (say) 2, we want to change the cage to be [(2, 1), (2, 4)]. But when that happens, it's necessary to change cell C2 to point to the new cage -- and of course since the cell was changed the construct that held that cell has to be changed also. It's a bit of a pain to write the code to do all that. This isn't to say that the code will take that long to run or that it will use excessive memory -- only that it feels like one is being forced to write code that one shouldn't have to write. * -- Russ * On Thu, Nov 25, 2010 at 9:42 AM, Ozgur Akgun wrote:

On 25 November 2010 17:12, Russ Abbott wrote:

...

Thanks, Patrick. I'm disappointed, though, that no one has actually responded to my question. It wasn't how to solve KenKen. It was how best to deal with quasi-mutable data structures.

You gave an example about how your data structure look like, but I haven't seen an example case of "quasi-mutating" an expression of such data structures. If you give a concrete example, people can suggest better ways of doing it, if there are any.

Best, Ozgur