[Haskell-beginners] how to undertand the function join (*)

[Ray]

Hello Marcus,

what does join (*) do?

 

(*) :: Num a => a -> a -> a

join (*) :: Num a => a -> a




when we feed a number to join (*),for instance;

 λ> : join (*) 3 

 9

it seems thata join (*) become a square function.

what does join do to  (*) to make that happen?
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