import "Prelude"

// --- Signals ------------------------------------------------------

data Signal =
    SigSum [Signal]
  | SigConst Double
  | SigNeg Signal
  | SigMul [Signal]

deriving instance Show Signal

instance Additive Signal where
    zero = SigConst 0
    a + b = SigSum [a,b]
    sum l = SigSum l

instance Ring Signal where
    one = SigConst 1
    neg a = SigNeg a
    fromInteger i = SigConst (fromInteger i)
    a * b = SigMul [a,b]

/*
instance Real Signal where
    fromDouble d = SigConst d
*/

main :: Signal
main = 1 + 2 * 3 - 4 
--
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