Constructing Cases

[Carl McTague]

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