Constructing Cases

Hi there, is there a simple way to carry out the following type of conversion? Suppose I have a list (finite) of (value,image) pairs such as: list = [(0,1),(1,0)]

From this I want to generate a function

f 0 = 1 f 1 = 0 Is there a way to do this? Note, I don't want to define a function that searches through the list each time it is invoked, I want to generate the function once and have it be as fast as the pattern-matcher can make it. So, I'm looking for a function g :: [(a,b)] -> a -> b Is this simple to do? Thanks, Carl