traits

Standard Traits Library (std/traits.qz)

Core traits for common operations. Traits can have abstract methods (bodyless — must be implemented) and default methods (have a body — inherited if not overridden).

Auto-satisfaction: If a type’s inherent impl already provides a method matching a trait requirement, the trait is automatically satisfied. Empty impl blocks are idiomatic: impl Container for Queue end.

Equality & Ordering

Eq

Equality comparison. Method names match operator dispatch: op_eq enables ==, op_ne enables !=.

trait Eq
  def op_eq(self, other: Self): Bool   # abstract
  def op_ne(self, other: Self): Bool   # default: not op_eq(self, other)
end

Implementations: impl Eq for String (via str_eq), impl Eq for Bytes (element-wise).

Ord

Ordering comparison. All defaults derived purely from op_lt — no Eq dependency.

trait Ord
  def op_lt(self, other: Self): Bool   # abstract
  def op_le(self, other: Self): Bool   # default: not op_lt(other, self)
  def op_gt(self, other: Self): Bool   # default: op_lt(other, self)
  def op_ge(self, other: Self): Bool   # default: not op_lt(self, other)
end

Arithmetic & Indexing

Add, Sub, Mul, Div, Mod

Each trait has one abstract method matching operator dispatch.

trait Add
  def op_add(self, other: Self): Self  # abstract — enables +
end

Same pattern for Sub (op_sub, -), Mul (op_mul, *), Div (op_div, /), Mod (op_mod, %).

Index

Enables obj[key] via op_index.

trait Index
  def op_index(self, key: Int): Int    # abstract
end

Common Traits

Hash

Hash code generation for use in hash maps.

trait Hash
  def hash(self): Int                  # abstract
end

Show

String representation. Has a sensible default.

trait Show
  def show(self): String               # default: "<unknown>"
end

Implementations: impl Show for JsonValue (via json_stringify), impl Show for TomlValue (via toml_stringify_value).

Clone

Value copying. Default returns self (works for small/primitive types).

trait Clone
  def clone(self): Self                # default: self
end

Serializable

JSON conversion.

trait Serializable
  def to_json(self): Int               # abstract
end

Implementations: impl Serializable for JsonValue.

Resource Management

Drop

RAII cleanup. The compiler inserts drop() calls automatically at scope exit, return, break/continue, and ? operator early return. Drop calls are in LIFO order.

trait Drop
  def drop(self): Void                 # abstract
end

Collections

Container

Common interface for sized collections. size and clear are abstract; is_empty has a sensible default.

trait Container
  def size(self): Int                  # abstract
  def is_empty(self): Bool             # default: self.size() == 0
  def clear(self): Void                # abstract
end

Implementations: Queue, Stack, Deque, LinkedList — all via auto-satisfaction from inherent impl methods.

Iterator<T>

Core iteration protocol. Returns Option::Some(value) for each element, Option::None when exhausted.

trait Iterator<T>
  def next(self): Option<T>            # default: Option::None
end

AsyncIterator<T>

Async iteration protocol for for await x in source.

Iterable<T>

Types that can produce an iterator via iter().

Deriving Traits

Use @derive to auto-generate trait implementations for structs:

@derive(Eq, Hash, Show, Clone, Ord)
struct Point
  x: Int
  y: Int
end