Целый квадратный корень из числа

d003.hs:16:53:
    No instance for (RealFrac Integer)
      arising from a use of `floor'
    Possible fix: add an instance declaration for (RealFrac Integer)
    In the expression: floor
    In the expression: (floor $ sqrt x)
    In the second argument of `notDevisible', namely
      `[2 .. (floor $ sqrt x)]'
 
d003.hs:16:61:
    No instance for (Floating Integer)
      arising from a use of `sqrt'
    Possible fix: add an instance declaration for (Floating Integer)
    In the second argument of `($)', namely `sqrt x'
    In the expression: (floor $ sqrt x)
    In the second argument of `notDevisible', namely
      `[2 .. (floor $ sqrt x)]'

Prelude> :t sqrt
sqrt :: Floating a => a -> a
Prelude> :t fromIntegral
fromIntegral :: (Num b, Integral a) => a -> b
Prelude> let x = 10 :: Integer
Prelude> sqrt x
 
<interactive>:1:1:
    No instance for (Floating Integer)
      arising from a use of `sqrt'
    Possible fix: add an instance declaration for (Floating Integer)
    In the expression: sqrt x
    In an equation for `it': it = sqrt x
Prelude> sqrt $ fromIntegral x
3.1622776601683795
Prelude> floor $ sqrt $ fromIntegral x
3