functionName :: types
functionName arg1 ... argN = body
 
 
-- File   : Example.hs
-- Module : Example
 
module Example where
 
increase :: Integer -> Integer
increase x = x + 1

.

(f.g) x ==> f (g x)

$

eliminate parentheses

($) :: (a -> b) -> a -> b

Partial Function

not defined for all possible input values of its domain.