Question

I recently started Erlang, and I notice I constantly get ‘Warning: variable X is unused’ while compiling. For example, take the following function, which finds the maximum element in a list:

    max([Head|Tail]) ->        max(Head,Tail).      max(Element,[Head | Tail]) when Element < Head ->        max(Head,Tail);     max(Element,[Head | Tail]) ->        max(Element, Tail);     max(Element,[]) ->        Element. 

The compiler warns me that in the 3rd case of the function, Head is unused. How can the function be written without Head?

Answer 1

This should suppress the warning without being confusing:

max(Element,[_Head | Tail]) ->    max(Element, Tail);