rwlock

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 RwLock<T, A = GlobalAlloc> where A: Allocator {
    inner: RwLockInner<T, A>*;
}

RwLock<T>: read/write reader-writer lock around a value.

type parameter A

where A: Allocator

type struct GlobalAlloc {}

Zero-sized handle to the process-wide allocator. Construct with GlobalAlloc::new(); all instances dispatch through the same underlying backend.

where T: Ord + Clone, U: Hash

Constrains generic parameters to types that implement the listed traits, which is what makes those traits' methods callable on T. Bounds on one parameter join with +; parameters separate with ,. A where on a single method narrows the type's parameter for that method only.

type parameter A

where A: Allocator

type trait Allocator {
    allocate(mut &this, layout: Layout) -> Result<NonNull<u8>, AllocError>;
    deallocate(mut &this, ptr: NonNull<u8>, layout: Layout) -> void;
    reallocate(mut &this, ptr: NonNull<u8>, old_layout: Layout, new_layout: Layout) -> Result<NonNull<u8>, AllocError>;
}

Allocator: the trait every heap strategy implements.

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 RwLock<T, A = GlobalAlloc> where A: Allocator {
    inner: RwLockInner<T, A>*;
}

RwLock<T>: read/write reader-writer lock around a value.

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

Result: a value that may be an error.

RwLock::read(&this) -> RwLockReadGuard<T, A>

Acquire a shared read lock, blocking until available.

&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 RwLockReadGuard<T, A> {
    inner: RwLockInner<T, A>*;
}

Shared-read guard. Many of these may exist concurrently on the same RwLock. Calling .as_ptr() yields a pointer that should be treated as &T (read-only); writing through it is a logic error the type system doesn't catch (Cryo has no borrow checker).

type enum Option<T> {
    Some(T);
    None;
}

Option: a value that may be absent.

RwLock::write(&this) -> RwLockWriteGuard<T, A>

Acquire the exclusive write lock, blocking until no other readers or writers hold it.

type struct RwLockWriteGuard<T, A> {
    inner: RwLockInner<T, A>*;
}

Exclusive write guard. At most one of these exists on a given RwLock, and no RwLockReadGuard can co-exist with it.

type struct RwLockReadGuard<T, A> {
    inner: RwLockInner<T, A>*;
}

Shared-read guard. Many of these may exist concurrently on the same RwLock. Calling .as_ptr() yields a pointer that should be treated as &T (read-only); writing through it is a logic error the type system doesn't catch (Cryo has no borrow checker).

type struct RwLockWriteGuard<T, A> {
    inner: RwLockInner<T, A>*;
}

Exclusive write guard. At most one of these exists on a given RwLock, and no RwLockReadGuard can co-exist with it.

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::sync;

std::sync: synchronization primitives for concurrent code.

namespace std::sync::rwlock;

RwLock<T>: read/write reader-writer lock around a value.

type struct Mutex<T, A = GlobalAlloc> where A: Allocator {
    inner: MutexInner<T, A>*;
}

Mutex<T>: mutual-exclusion lock around a value.

RwLock::read(&this) -> RwLockReadGuard<T, A>

Acquire a shared read lock, blocking until available.

RwLock::write(&this) -> RwLockWriteGuard<T, A>

Acquire the exclusive write lock, blocking until no other readers or writers hold it.

implement struct Name { ... }
implement trait Trait for Type { ... }
implement u64 { ... }

Adds methods to a type outside its declaration. implement struct T (or enum, or a bare primitive) opens an inherent block; implement trait Tr for T supplies a trait's methods for one type. Resolution is at compile time - no dynamic dispatch.

type trait Name : Base {
    method(&this, other: &This) -> Ret;
}

Names a set of methods a type may implement. Inside the body This is the implementing type; methods may carry default bodies, and a trait may require a base trait (type trait Ord : Eq). Generic code asks for a trait with where T: Name.

type trait Drop {
    drop(mut &this) -> void;
}

Drop: explicit destructor.

implement trait Trait for Type { ... }

Names the type a trait implementation is for. The block that follows supplies the bodies the trait requires.