join string lists

[GOTO10]

I'm curious to hear from some of the more experienced coders on the forum what they think is the best way to do this. I understand that it's generally considered desirable to avoid using range(len(sequence)), but I'm having a hard time doing so without adding lines of code or checks I wouldn't need otherwise.

Here is what I came up with:

l = ['a', 'b', 'c', 'd']
newl = []

for i in range(len(l) -1):
    newl.append(''.join(l[i] + l[i+1]))

print(newl)