Source

Prelude

1. foldr (+) 0 [1, 2, 3] == 6
2. foldr (+) 0 (1 : [2, 3]) == 6
3. 1 + foldr (+) 0 [2, 3] == 6
4. 1 + foldr (+) 0 (2 : [3]) == 6
5. 1 + (2 + foldr (+) 0 [3]) == 6
6. 1 + (2 + foldr (+) 0 (3 : [])) == 6
7. 1 + (2 + (3 + foldr (+) 0 [])) == 6
8. 1 + (2 + (3 + 0)) == 6
9. 1 + (2 + 3) == 6
10. 1 + 5 == 6
11. 6 == 6
12. True