This is want I needed to hear. I haven't used either Clean nor Haskell other than playing with them and my introduction to Clean seemed more lightweight where there some syntax to make uniqueness seem easier than the same in Haskell. On further reading, when seeing the u:[...] syntax rather than * I can see they're really quite the same. They way the uniqueness attributes are described seems like a separate axis than data types where in Haskell there's just so much type. Also the docs for Clean avoids using category theory terms for the most part, getting you started by showing you the syntax to do certain things.

I expect to be coming back to this comment and the references quite a few times until it clicks for me.