Hi,

I need a container data structure for storing anonymous objects - most likely things that have not value such as STM (), but probably other things as well. This will allow me to later on, iterate over the container and process those objects. Additionally I have the requirement that I need to be able to remove individual objects from this container. It needs to be linear time.

main = do
   container <- nil
   key1 <- cons 1 container
   key2 <- cons 2 container
   key3 <- cons 3 container
   key4 <- cons 4 container
   key5 <- cons 5 container
   unlink key3 container
   unlink key2 container
   unlink key4 container
   list <- toList container
   putStrLn (show list)

The above should give: [1, 5]

What should I use?

Thanks

-John