[Haskell-beginners] Re: question about styles of recursion

[7stud]

Daniel Fischer <daniel.is.fischer <at> web.de> writes:
>
> (/) in the first equation is at type Double -> Double -> Double.
>

Then why don't I get an error here:

Prelude> 2 / 4
0.5
Prelude> 2 / fromIntegral 4
0.5

And why does this happen:

Prelude> let x = 2
Prelude> :type x
x :: Integer
Prelude> x / fromIntegral 4

<interactive>:1:0:
    No instance for (Fractional Integer)
      arising from a use of `/' at <interactive>:1:0-17
    Possible fix: add an instance declaration for (Fractional Integer)
    In the expression: x / fromIntegral 4
    In the definition of `it': it = x / fromIntegral 4


And how do I read this type:

Prelude> :type fromIntegral
fromIntegral :: (Num b, Integral a) => a -> b

What does the => mean?