Python: recursive generator

Question

I want to recursively generate all the possible sums of the slices of a string of digits. For example:

Input: '891'
Output: 18, 99, 90, 891

In details:
    8+9+1 = 18
    8+91 = 99
    89+1 = 90
    891 = 891

However, the code I wrote yields generators of generators:

# s: string of digits, c: sum of slices
def rec(s,c):
    for i in range(1,len(s)+1):
        if s=='': yield c
        else: yield rec(s[i:],c+int(s[:i]))

How can I fix it?

Answer 1

It can sometimes be tricky to get right. But you are confusing yourself by adding the extra argument:

def rec(s):
    # No split.
    yield int(s)

    # Split.
    for i in range(1, len(s)):
        left = int(s[:i])
        for right in rec(s[i:]):
           yield left + right

And indeed:

>>> list(rec("891"))
[891, 99, 18, 90]