I encountered a new problem which is I want to get " 1 " from a triple
"(0,2,[1,2,3])", which means I want to get the first value of the third item
in one triple and itself is a list, but when I use the List.hd
(third(0,2,[1,2,3])), it will give me the entire list which is [1,2,3]
the definition of the third is "let third(x,y,z)=z", so is there a way I can
get out "1" from "(0,2,[1,2,3])"? if possible, would you please give me some
advices?

thank you very much

-- 
Su Zhang