A non-working way of listing factors in haskell

code

isDivisor :: (Integral a) => a -> a -> b
isDivisor number divisor = ((number `mod` divisor) == 0)

l_factors :: (Integral a) => a -> a -> [a] -> [a]
l_factors 1 target list = list
l_factors divisor target list
     | isDivisor target divisor = (l_factors divisor-1 target/divisor divisor:list)
     | otherwise = (l_factors divisor-1 target divisor:list)

error

[1 of 1] Compiling Main             ( problem3.hs, interpreted )

problem3.hs:9:36:
    Couldn't match type `a' with `a -> [a] -> [a]'
      `a' is a rigid type variable bound by
          the type signature for
            l_factors :: Integral a => a -> a -> [a] -> [a]
          at problem3.hs:7:1
    In the return type of a call of `l_factors'
    In the first argument of `(-)', namely `l_factors divisor'
    In the first argument of `(:)', namely
      `l_factors divisor - 1 target / divisor divisor'

problem3.hs:9:63:
    Couldn't match type `a' with `a -> a'
      `a' is a rigid type variable bound by
          the type signature for
            l_factors :: Integral a => a -> a -> [a] -> [a]
          at problem3.hs:7:1
    The function `divisor' is applied to one argument,
    but its type `a' has none
    In the second argument of `(/)', namely `divisor divisor'
    In the second argument of `(-)', namely
      `1 target / divisor divisor'

problem3.hs:10:21:
    Couldn't match type `a' with `a -> [a] -> [a]'
      `a' is a rigid type variable bound by
          the type signature for
            l_factors :: Integral a => a -> a -> [a] -> [a]
          at problem3.hs:7:1
    In the return type of a call of `l_factors'
    In the first argument of `(-)', namely `l_factors divisor'
    In the first argument of `(:)', namely
      `l_factors divisor - 1 target divisor'
Failed, modules loaded: none.

[1 of 1] Compiling Main             ( problem3.hs, interpreted )

problem3.hs:5:29:
    Could not deduce (b ~ Bool)
    from the context (Integral a)
      bound by the type signature for
                 isDivisor :: Integral a => a -> a -> b
      at problem3.hs:5:1-56
      `b' is a rigid type variable bound by
          the type signature for isDivisor :: Integral a => a -> a -> b
          at problem3.hs:5:1
    In the expression: ((number `mod` divisor) == 0)
    In an equation for `isDivisor':
        isDivisor number divisor = ((number `mod` divisor) == 0)
Failed, modules loaded: none.

l_factors :: (Integral a) => a -> a -> [a] -> [a]
l_factors 1 target list = list
l_factors divisor target list
| isDivisor target divisor = l_factors (divisor-1) (div target divisor) (divisor:list)
| otherwise = l_factors (divisor-1) target (divisor:list)