Still not convinced with the reasoning, I'm afraid, but I certainly agree that modifications to built-ins are not to be made lightly. Using deques, which are far less familiar, is not a particularly natural thing to do for a search path, and of course can't be used with a built-in list to which you might well wish to prepend: sys.path.

Personally, I would have no problem with a list pop_front method ;) I understand the connection of API availability and misuse of algorithmically inefficient methods -- for large lists -- but I don't find "be inconveniently absent so that users search for an answer and find out about complexity issues" a very compelling or Pythonic design aim. But I admit that l.insert(0, x) is not such a hard idiom to learn -- just a bit less syntactically elegant and self-explanatory than I would prefer for a simple task, especially where I've already conciously made the efficiency decision in my choice of container type.

But thanks for listening... as mentioned, this can stay here as a reference for further enquiries (I searched for a pre-existing prepend() request before submitting this ticket, of course!) and I'll go visit python-ideas. Cheers!