string to dictionary

[les ander]

Hi, 
i have a list of strings like this:

aList=[ 'a_1 b_1', 'a_2 b_2', 'a_3 b_3',...]

i want to convert this to a dictionary with a_i -> b_i without
using loops (it is trivial to do it with loops)
i tried this 

dict={}
map(lambda x,d=dict: c=string.split(x), d[c[0]]=c[1], aList)

but it complains that "keyword can't be an expression"
can someone please help me get this right?
thanks
les