No, you still have to copy "aaaa" so you can change the tail pointer

Do you? If "aaaa" is treated as a single buffer contents (IE implemented as a UArray Int Char for example) then as our 'new' list implementation# can have cells which are single elements of buffers of elements, we simply 'cons' the buffer onto the beginning of the list (IE the next pointer is not in the constants string but the cell containing it) Keean.