URLs (std::url)

std::url provides pure utilities for working with web addresses: decomposition into parts, percent-encoding and decoding, and query string assembly. Because all operations are local computations (no network or filesystem), the examples run directly in the sandbox.

URL parsing

url.parse breaks an address into protocol, host, port, path, query, fragment and a params map with the parameters already decoded.

Extracts each component of a full URL, including params.

01-parse.zolo

Playground

// Feature: url.parse — break a URL into protocol, host, port, path, query, fragment
// When to use: extract parts of an address for routing, validation, or logging.

use std::url

let parts = url.parse("https://api.example.com:8443/users/42?id=42&active=true#bio")

print(parts["protocol"])  // expected: https
print(parts["host"])  // expected: api.example.com
print(parts["port"])  // expected: 8443
print(parts["path"])  // expected: /users/42
print(parts["query"])  // expected: id=42&active=true
print(parts["fragment"])  // expected: bio

// Query params are already parsed into params.
print(parts["params"]["id"])  // expected: 42
print(parts["params"]["active"])  // expected: true

Percent-encoding and decoding

url.encode / url.decode handle spaces and special characters; the encode_component / decode_component variant is more aggressive and also escapes /, ? and # — ideal for values inside a query string.

Round-trip between a raw string and its percent-encoded representation.

02-encode-decode.zolo

Playground

// Feature: url.encode / url.decode — percent-encoding
// When to use: pass strings with spaces or special characters in URLs.

use std::url

// encode applies percent-encoding to non-safe characters.
let raw = "hello world & friends"
let enc = url.encode(raw)
print(enc)  // expected: hello%20world%20%26%20friends

// decode reverses the operation.
print(url.decode(enc))  // expected: hello world & friends

// encode_component is more aggressive — it also escapes /, ?, #.
let comp = url.encode_component("a/b?c=d")
print(comp)  // expected: a%2Fb%3Fc%3Dd

let back = url.decode_component(comp)
print(back)  // expected: a/b?c=d

Building query strings

Combine url.encode_component with concatenation and Array.join to build query strings dynamically without relying on external libraries.

Parsing existing params and manually building an encoded query string.

03-query-string.zolo

Playground

// Feature: url — build and parse query strings

// When to use: HTTP clients, links with filters, pagination.


use std::Array
use std::url

// Parse: query string already comes in `params` when using url.parse.

let parts = url.parse("https://api.example.com/search?q=zolo+lang&page=2&limit=20")
print(parts["params"]["q"])  // expected: zolo+lang

print(parts["params"]["page"])  // expected: 2

print(parts["params"]["limit"])  // expected: 20


// Manual construction: join "k=v" pairs with "&".

fn build_query(pairs: [str]) -> str {
  return pairs.join("&")
}

let qs = build_query([
  "q=" + url.encode_component("hello world"),
  "page=1",
  "active=true",
])
print(qs)  // expected: q=hello%20world&page=1&active=true

Challenge

Given a map #{ q: "zolo lang", page: 1 }, write a to_query_string function that iterates the keys and produces q=zolo%20lang&page=1.