Hello,
The function (++) :: [x] -> [x] -> [x] has O(n) complexity.
If somebody were to invent some type that looks like [x] but actually uses some sort of tree rather than a linked list, you should be able to get O(1) concatenation. Has anybody ever implemented such a thing?
You can also do this with a functional representation of lists (i.e. lists are functions); this idea is usually called difference lists. There is a nice dlist library on hackage. -Jeff --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.