[Haskell-cafe] Ignorant begginer question

[Maurício]

   Guys,

   What is wrong with this code?

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import Complex
roots :: (Complex, Complex, Complex) -> (Complex, Complex);
roots (a,b,c) = (x1,x2) where { x1 = (b*b + (sqrt_delta))/(2*a); x2 = 
(b*b - (sqrt_delta))/(2*a); sqrt_delta = sqrt 4*a*c}
**************

   I load it into GHCi and get:

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Kind error: `Complex' is not applied to enough type arguments
In the type: (Complex, Complex, Complex) -> (Complex, Complex)
While checking the type signature for `roots'
Failed, modules loaded: none.
**************

   Thanks,
   Maurício