container_and_sequence_operations.md

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Container & Sequence Operations

This page documents all user-facing container and sequence APIs for var, in a clear tabular format with concise examples.

---

Core Container Operations

API / Method	Description	Example
len(v) / size(v)	Get length/size of container	len(list(1,2,3)) // 3
v.size()	Member: get size	vlist.size()
append(const var &v)	Append element to list	vlist.append(4)
add(const var &v)	Add element to set/ordered_set	vset.add(5)
extend(const var &other)	Extend list/set with another container	vlist.extend(list(4,5))
update(const var &other)	Update set/dict with another container	vset.update(set(6,7))
remove(const var &v)	Remove element from container	vlist.remove(2)
contains(const var &v)	Check if element is in container	vlist.contains(2)
has(const var &v)	Alias for contains	vset.has(3)
clear()	Remove all elements	vlist.clear()
empty()	Check if container is empty	vlist.empty()
front() / back()	Get first/last element (list)	vlist.front(), vlist.back()
pop()	Remove and return last element (list)	vlist.pop()
at(index)	Access element by index (list)	vlist.at(1)
operator[](index)	Indexing (list/dict)	vlist[1], vdict["a"]
items()	Dict: get key-value pairs	vdict.items()
keys()	Dict: get keys	vdict.keys()
values()	Dict: get values	vdict.values()
slice(start, end, step)	List: get sublist	vlist.slice(1,3)
operator()(...)	List: slicing via call syntax	vlist(1,3)
begin()/end()/cbegin()/cend()	Iterators for C++ loops	for (auto it = vlist.begin(); it != vlist.end(); ++it) ...

---

Examples

#include <pythonic/pythonic.hpp>
using namespace py;

int main()
{
    var vlist = list(1, 2, 3);
    vlist.append(4);           // [1,2,3,4]
    vlist.extend(list(5,6));   // [1,2,3,4,5,6]
    vlist.remove(2);           // [1,3,4,5,6]
    print(vlist.len());       // 5
    print(vlist.front());      // 1
    print(vlist.back());       // 6
    print(vlist.at(2));        // 4
    print(vlist[1]);           // 3
    print(vlist.slice(1,4));   // [3,4,5]
    print(vlist(1,4));         // [3,4,5]
    print(vlist.empty());      // false
    vlist.clear();
    print(vlist.empty());      // true

    var vset = set(1,2,3);
    vset.add(4);
    vset.update(set(5,6));
    print(vset.contains(3));    // true
    print(vset.has(5));        // true
    vset.remove(1);

    var vdict = dict({{"a", 1}, {"b", 2}});
    print(vdict["a"]);        // 1
    print(vdict.keys());       // ["a", "b"]
    print(vdict.values());     // [1,2]
    print(vdict.items());      // [("a",1), ("b",2)]
    for (auto it = vdict.get<Dict>().begin(); it != vdict.get<Dict>().end(); ++it) 
    {
        print("key: ", it->first);  // key (std::string)
        print("value: ", it->second); // value (var)
    }
    for (auto [key,value] : vdict.get<Dict>())
    {
        print("key: ", key);  // key (std::string)
        print("value: ", value); // value (var)
    }
    for (auto it = vdict.begin(); it != vdict.end(); ++it) 
    {
        print(1);
        // but you can't use it->first and it->second here as the vdict is not a std::map. also you can not do auto[key,value] like iteration directly on vdict, you have to use vdict.get<Dict>() to get the underlying std::map
    }
    return 0;
}

---

Functional Helpers

Function	Description	Example(s)
reversed_var(list)	Return a new list with elements in reverse order	reversed_var(list(1,2,3)) // [3,2,1]
reversed_var(str)	Return a new string with characters reversed	reversed_var("abc") // "cba"
all_var(list)	True if all elements are truthy	all_var(list(1,2,3)) // true all_var(list(1,0,3)) // false
any_var(list)	True if any element is truthy	any_var(list(0,0,3)) // true any_var(list(0,0,0)) // false
map(func, list)	Apply a function to each element, return new list	map(lambda x: x+1, list(1,2,3)) // [2,3,4]
filter(pred, list)	Filter elements by predicate, return new list	filter(lambda x: x>1, list(1,2,3)) // [2,3]
reduce(func, list, initial)	Reduce list to single value with binary function, starting from initial	reduce(lambda a,b: a+b, list(1,2,3), 10) // 16
reduce(func, list)	Reduce list to single value with binary function	reduce(lambda a,b: a+b, list(1,2,3)) // 6

---

Examples

#include "pythonic/pythonic.hpp"
using namespace py;

// --- reversed_var ---
var vlist = list(1, 2, 3);
var vstr = "hello";
var revlist = reversed_var(vlist);    // [3, 2, 1]
var revstr = reversed_var(vstr);      // "olleh"

// --- all_var / any_var ---
var alltrue = all_var(list(1, 2, 3)); // true
var somefalse = all_var(list(1, 0, 3)); // false
var anytrue = any_var(list(0, 0, 3)); // true
var allfalse = any_var(list(0, 0, 0)); // false

// --- map ---
auto add1 = [](const var &x) { return x + 1; };
var mapped = map(add1, list(1, 2, 3)); // [2, 3, 4]

// --- filter ---
auto greater1 = [](const var &x) { return x > 1; };
var filtered = filter(greater1, list(1, 2, 3)); // [2, 3]

// --- reduce ---
auto sum2 = [](const var &a, const var &b) { return a + b; };
var reduced = reduce(sum2, list(1, 2, 3)); // 6
var reduced_init = reduce(sum2, list(1, 2, 3), 10); // 16

---

Notes

• Use len(v) or v.size() for container length.
• Use append, add, extend, update, remove for mutating containers.
• Use contains/has to check membership.
• Use slice or call syntax for sublists.
• Use items, keys, values for dicts.
• Iterators allow C++-style for loops over containers.

Next check

• String-like Methods (on string var)