Generating All Strings of a Given Alphabet

For a recent research project, I had to write a function that generates all the strings of a given alphabet. It was (as always) very easy to figure it out in Python, only 5 minutes; below is the code (with mod­i­fi­ca­tions, I've polished the idea a bit):

def allstrings(alphabet, length):
    """Find the list of all strings of 'alphabet' of length 'length'"""

    if length == 0: return []

    c = [[a] for a in alphabet[:]]
    if length == 1: return c

    c = [[x,y] for x in alphabet for y in alphabet]
    if length == 2: return c

    for l in range(2, length):
        c = [[x]+y for x in alphabet for y in c]

    return c

Then, suppose you want the possible strings of length 4 of alphabet {1,2,3}; then just write:

allstrings([1,2,3], 4)

And here is the Haskell version:

allstrings alphabet n
 | n == 0 = []
 | n == 1 = [alphabet]
 | n == 2 = [[a,b] | a<-alphabet, b<-alphabet]
 | otherwise =
   [[a] ++ b | a<-alphabet, b<-(allstrings alphabet (n - 1))]