client

type struct Name { ... }
type enum Name { ... }
type trait Name { ... }
type union Name { ... }

Begins a type declaration; the keyword that follows says which kind. On its own, type Name = Existing; declares an alias.

type struct Name {
    field: Type;
    method(&this) -> Ret { ... }
}

A value type with named fields and optional methods. Structs live on the stack and are passed by value. Fields are public by default and may carry = default values; methods take their receiver as &this, mut &this, or this.

type struct Client {}

HTTP client: simple one-shot requests over plain TCP.

static name(param: Type) -> Ret { ... }

A method that belongs to the type rather than an instance, called as Type::name(..). For structs, static new(..) returning a struct literal is the idiomatic constructor.

type struct Client {}

HTTP client: simple one-shot requests over plain TCP.

async function name(param: Type) -> T { ... }

Compiles the function into a stackless state machine. Calling it builds a future whose output is the declared return type; nothing runs until that future is polled. Allowed on free functions, methods, and trait methods.

async Client::get(&this, addr: SocketAddr, path: Str) -> Result<Response, IoError>

GET addr/path. Sets Host to addr's address:port.

&this
mut &this
this

The receiver of a method. Its first parameter declares how the method takes it: &this borrows read-only, mut &this borrows exclusively, and this / mut this move the value in and consume it. In the body, this.field reaches the members.

type struct SocketAddr {
    ip: IpAddr;
    port: u16;
}

SocketAddr: (IP, port).

type struct Str {
    bytes: u8*;
    length: u64;
}

Str: a borrowed UTF-8 string slice.

type enum Result<T, E> {
    Ok(T);
    Err(E);
}

Result: a value that may be an error.

type struct Response {
    status: StatusCode;
    version: String;
    headers: Headers;
    body: Array<u8>;
}

HTTP response.

async Client::post(&this, addr: SocketAddr, path: Str, content_type: Str, body: Array<u8>) -> Result<Response, IoError>

POST addr/path with body bytes. Sets Host and passes the supplied Content-Type through unchanged; if the caller didn't set one, the server may fall back to octet-stream.

type struct Array<T, A = GlobalAlloc> where A: Allocator {
    ptr: T*;
    length: i64;
    capacity: i64;
    alloc: A;
}

Array<T, A>: growable, heap-backed, contiguous sequence.

primitive u8

8-bit unsigned integer.

import a::b;
import a::b::{ X, Y };
import a::b as c;
import a::b::*;

Brings a module, or selected items from it, into scope. One path per declaration: use the brace form for several items, as to alias, and * for everything public (prefer the brace form; wildcards invite name collisions).

namespace std;

std: the Cryo standard library.

namespace std::net;

net: network primitives + HTTP.

namespace std::net::http;

http: HTTP/1.1 with keep-alive.

namespace std::net::http::client;

HTTP client: simple one-shot requests over plain TCP.

mut name: Type = value;

A mutable binding, reassignable after declaration - mutability is opt-in, const is the default. At module level it declares mutable global state. Before & it marks an exclusive reference or receiver instead.

const NAME: Type = value;

At module level, a true compile-time constant, conventionally SCREAMING_SNAKE_CASE. (mut at module level declares mutable global state instead.)

async Client::get(&this, addr: SocketAddr, path: Str) -> Result<Response, IoError>

GET addr/path. Sets Host to addr's address:port.

static Str::new(text: string) -> Str

Construct from a NUL-terminated C-style string literal. The caller certifies that text is valid UTF-8 and outlives this view. The NUL terminator is not included in the view.

async Client::post(&this, addr: SocketAddr, path: Str, content_type: Str, body: Array<u8>) -> Result<Response, IoError>

POST addr/path with body bytes. Sets Host and passes the supplied Content-Type through unchanged; if the caller didn't set one, the server may fall back to octet-stream.

async function send(addr: SocketAddr, req: Request) -> Result<Response, IoError>

Open a connection, send the request, read one response, close. Emits Connection: close (RFC 7230 section 6.1) so the server knows this is a one-shot exchange and can free its half of the socket as soon as the response is written.

function close(fd: i32) -> i64

close(2): release fd. Returns 0 on success, or -errno.

function name<T>(param: Type) -> Ret { ... }

Declares a function. Parameters are written name: Type and are never inferred; the return type follows -> and defaults to void. Declaration order does not matter: every signature is collected before any body is checked, so functions may call each other freely and recurse.

async function send(addr: SocketAddr, req: Request) -> Result<Response, IoError>

Open a connection, send the request, read one response, close. Emits Connection: close (RFC 7230 section 6.1) so the server knows this is a one-shot exchange and can free its half of the socket as soon as the response is written.

type struct Request {
    method: Method;
    path: String;
    version: String;
    headers: Headers;
    body: Array<u8>;
    params: HashMap<String, String>;
}

HTTP request.