Rust Platform

🎯 In Python, converting between collection types is effortless:

numbers = [3, 1, 2, 1, 3]
unique = set(numbers)          # {1, 2, 3}
sorted_list = sorted(unique)   # [1, 2, 3]

pairs = [("a", 1), ("b", 2)]
lookup = dict(pairs)           # {"a": 1, "b": 2}

from collections import Counter
Counter(["red", "blue", "red"])  # {'red': 2, 'blue': 1}

You call set(), dict(), list(), sorted() — the constructor does the work. In Rust, one method does all of this: .collect(). What it collects into depends on the type annotation.

.collect() — one method, many targets

.collect() consumes an iterator and builds a collection. The type annotation tells Rust which collection to create:

let v: Vec<i32> = (1..=5).collect();           // [1, 2, 3, 4, 5]

use std::collections::HashSet;
let set: HashSet<i32> = (1..=5).collect();     // {1, 2, 3, 4, 5}

let s: String = vec!['h', 'i'].into_iter().collect();  // "hi"

Same iterator, same .collect() call — different results. This is …