Basic Functions

A basic function in Haskell can be compared to a math function.

• Incrementer

f(x)=x+1

What this function do is to transform a number x into a number x+1 (ex: f(1)=2).

In  Haskell, we write this function by the same way, where f is the name of the function and x is the argument and x+1 is the result.

The type of this f function would be

f :: Int -> Int

Note that the f function receives an int value (x) and returns another int (x+1)

(Click here to get more info about types)

So this function can be written like this:
f :: Int->Int
f x = x+1

• Greater

Now, imagine a function called greater that receives two numbers and check if the first is greater than the second, e.x. greater 4 3 = True; greater 3 4 = False.
The type of this function is

greater :: Int -> Int -> Bool

And should be,initially, declared by this way

greater x y = if(x>y) then True else False

But the function >, declared at Prelude (where the basic functions, such as the sum, greater, etc, are declared), already returns a boolean value (True or False), so the declaration of the greater function can be done by this way:

greater x y = x>y

or in the extreme case

greater = >