After discussing with Armin and Holger, I have created a new branch to explore typed unwrapping. This was touched and discussed also in the past, we would like to move away from the current generic unwrap to typed versions thereof, also because is a reasonable way to express type information about parameters that enters functions (for example builtin function implementations) as just generic object and then get unwrapped. As first step we will introduce str_w and int_w space operations, that are type specific unwraps for string and integers. Removing generic unwrapping of lists and tuples (probably up to their usage in tests) makes also sense, because in mixed type cases they are problematic as RPython operations. After this we discussed about supplying the gateways with specifier so that can also carry out unwrapping and argument type checking int the spirit of CPython ParseTuple* operations. For that we will likely need typed unwrapping for more types and to think about the issues of unwrapping vs. going first through the various __int__, __str__ conversion special methods. Samuele.