[Haskell-cafe] Re: Could someone teach me why we use Data.Monoid?

I have looked the concept of monoid and something related, but still, I do not know why we use it?

I don't know if it's a good example, but it's simple. This package I wrote uses reverse polish notation to write gtk2hs layout windows. http://hackage.haskell.org/package/gtk2hs-rpn Since the type for operators used in the stack is a Monoid instance, you can combine many of them to create new operators. I believe you can think of monoids as things you can sequence to make new ones of the same type, but someone with better knowledge please say if this is actually a misleading idea. Best, Maurício