-- switches the first element with the last element in a list
switch :: [a] -> [a]
switch [] = []
switch [a] = [a]
switch [a,b] = [b,a]
switch [a,b,c] = [c,b,a]
switch [a,b,c,d] = [d,b,c,a]
switch [a,b,c,d,e] = [e,b,c,d,a]
switch [a,b,c,d,e,f] = [f,b,c,d,e,a]