I wrote following program:

isPrime x = and [x `mod` i /= 0 | i <- [2 .. truncate (sqrt x)]]

primes = filter isPrime [1 .. ]

it should construct list of prime numbers. But I got this error:

[1 of 1] Compiling Main             ( 7/main.hs, interpreted )

7/main.hs:3:16:
    Ambiguous type variable `a' in the constraints:
      `Floating a' arising from a use of `isPrime' at 7/main.hs:3:16-22
      `RealFrac a' arising from a use of `isPrime' at 7/main.hs:3:16-22
      `Integral a' arising from a use of `isPrime' at 7/main.hs:3:16-22
    Possible cause: the monomorphism restriction applied to the following:
      primes :: [a] (bound at 7/main.hs:3:0)
    Probable fix: give these definition(s) an explicit type signature
                  or use -XNoMonomorphismRestriction
Failed, modules loaded: none.

If I specify signature for isPrime function explicitly:

isPrime :: Integer -> Bool
isPrime x = and [x `mod` i /= 0 | i <- [2 .. truncate (sqrt x)]]

I can't even compile isPrime function:

[1 of 1] Compiling Main             ( 7/main.hs, interpreted )

7/main.hs:2:45:
    No instance for (RealFrac Integer)
      arising from a use of `truncate' at 7/main.hs:2:45-61
    Possible fix: add an instance declaration for (RealFrac Integer)
    In the expression: truncate (sqrt x)
    In the expression: [2 .. truncate (sqrt x)]
    In a stmt of a list comprehension: i <- [2 .. truncate (sqrt x)]

7/main.hs:2:55:
    No instance for (Floating Integer)
      arising from a use of `sqrt' at 7/main.hs:2:55-60
    Possible fix: add an instance declaration for (Floating Integer)
    In the first argument of `truncate', namely `(sqrt x)'
    In the expression: truncate (sqrt x)
    In the expression: [2 .. truncate (sqrt x)]
Failed, modules loaded: none.

Can you help me understand, why am I getting these errors?