Re: Arrays and arrays

Any reason it couldn't be done in-place? (I.e. thaw, update all, and freeze again) Am I missing something -- Could partial results be used, the update list be infinite, or anything like that?

I believe that's essentially what normal arrays are doing, but that's not inplace. In the process of thawing, you're copying the array. If you're not copying it, then the results are unsound.