Thue-Morse sequence

{-  Print the first n elements of the Thue-Morse sequence. The Thue-Morse sequence
    is a binary sequence (it comprises of only 1's and 0's) beginning with 0, which
    is derived by repeatedly appending an inverted version of the sequence to the
    sequence itself. The first few iterations look like this:
        0
        01
        0110
        01101001
        0110100110010110
    etc. -}

main = interact $ concatMap show . flip take tmSequence . read
tmSequence = concat helper where
    helper = [0] : map (concatMap invert . flip take helper) [1..]
    invert = map (1 -)

-- Golfed (86 bytes)
main=interact$c.map show.(`take`c t).read
t=[0]:map(map(1-).c.(`take`t))[1..]
c=concat

-- Fibonacci
fib = 0 : 1 : zipWith (+) fib (tail fib)