Why do python lists have pop() but not push()
list, python
Solution
Because "append" existed long before "pop" was thought of. Python 0.9.1 supported list.append in early 1991. By comparison, here's part of a discussion on comp.lang.python about adding pop in 1997. Guido wrote:
To implement a stack, one would need to add a list.pop() primitive (and no, I'm not against this particular one on the basis of any principle). list.push() could be added for symmetry with list.pop() but I'm not a big fan of multiple names for the same operation -- sooner or later you're going to read code that uses the other one, so you need to learn both, which is more cognitive load.
You can also see he discusses the idea of if push/pop/put/pull should be at element [0] or after element [-1] where he posts a reference to Icon's list:
I stil think that all this is best left out of the list object implementation -- if you need a stack, or a queue, with particular semantics, write a little class that uses a lists
In other words, for stacks implemented directly as Python lists, which already supports fast append(), and del list[-1], it makes sense that list.pop() work by default on the last element. Even if other languages do it differently.
Implicit here is that most people need to append to a list, but many fewer have occasion to treat lists as stacks, which is why list.append came in so much earlier.
Problem
Does anyone know why Python's `list.append` method is not called `list.push`, given that there's already a `list.pop` that removes and returns the last element (indexed at `-1`) and `list.append` semantic is consistent with that usage?