Hi all,

I have a question on ocaml, is there a way to write a empty element say a
which can make a::ax=ax ? I tried to find out in library, yet I didn't get
the right way out, and it doesn't work if I make a=[], so do you know
whether there is a technique can realize this function?  I've got stuck on
this point for a very long time.

thanks

-- 
Su Zhang
PHD Student
Computer Information and Science
Kansas State University