Thank you very much for this nice intermediate solution, though I need constant-time append, split, insert, remove, + pointers to items, etc. Mutation does seem unavoidable, right. I started my own lib, but if something already exists, I'm still interested.
The purpose is to make a hash with bounded memory, with replacement of oldest items, or barely used items, or some other replacement criterion. The final purpose is to make a memoization form with bounded memory, or growing memory but with frequent removal of selected items. If I have time to get there. I'll keep the zipper in mind for other purposes though! Laurent On Tue, Aug 30, 2011 at 08:35, Danny Yoo <d...@cs.wpi.edu> wrote: > > Nothing obvious, no. But Racket is designed to encourage programming > without > > mutation, and doubly linked lists require mutation. > > > > It's very likely a zipper will do what you want. A zipper is much easier > to > > implement than a doubly linked list, and has similar performance and > uses. > > > To supplement, here are very old notes I wrote to myself on the kind > of list zipper that Neil is presenting: > > https://hkn.eecs.berkeley.edu/~dyoo/plt/zippers.txt > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users >
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