Haskell：无法推断由于使用“ cos”而引起的（浮动t）

我正在学习Haskell，我试图根据我在Internet上发现的资源来实现一些量子门。目前，我已经成功实现了Z门，X门，H门，但是实现旋转门时遇到了问题。

U = [[cos t  -sin t] 
     [sin t  cos t ]]

我写的代码：

type Vector a = [a]
type Matrix a = [Vector a]
vectorToComplex :: Integral a => Vector a -> Vector (Complex Double)
vectorToComplex = map (\i -> fromIntegral i:+0.0)
matrixToComplex :: Integral a => Matrix a -> Matrix (Complex Double)
matrixToComplex = map vectorToComplex
--Z Gate
gateZ :: Matrix (Complex Double)
gateZ = matrixToComplex [[1,0],[0,-1]]

我尝试以与实现Z门相同的方式实现gateR（旋转门）：
gateR :: Integral t => t -> Matrix (Complex Double) gateR t = matrixToComplex [[cos t,-sin t],[sin t,cos t]]
但是我遇到下一个错误，但我不太了解（我仍在学习该语言）。

Could not deduce (Floating t) arising from a use of `cos'
    from the context (Integral t)
      bound by the type signature for
                 gateR :: Integral t => t -> Matrix (Complex Double)
      at quantum.hs:66:8-44
    Possible fix:
      add (Floating t) to the context of
        the type signature for
          gateR :: Integral t => t -> Matrix (Complex Double)
    In the expression: cos t
    In the expression: [cos t, - sin t]
    In the first argument of `matrixToComplex', namely
      `[[cos t, - sin t], [sin t, cos t]]'