Appendix E: Glossary

Artifact

A compiled Whim unit stored in a .whia file.

Array

The common type of tuples, vecs, and dicts.

Attribute

A typed value attached to a declaration, member, or parameter.

Autoloader

Code that tries to define a symbol when Whim first needs it.

Backed enum

An enum whose cases each have an int or string value.

Bound

A type rule that limits a generic type argument.

Callable

A fn value created by a closure expression, first-class callable syntax, or partial function application.

Cancellation token

A value that tells a waiting operation to stop waiting.

Class family

A class and its parent and child classes.

Closure

An unnamed function written with fn. Its body is an expression or block, and it captures the outer variables it uses by value.

Constant expression

A source form allowed in constants and defaults. It cannot read a local variable or $this directly, but a call inside it may run code, inspect state, or throw.

Coroutine

A call stack that may pause and later continue on the event loop.

Dict

A mutable ordered array with bool, int, uint, string, or fresh keys.

First-class callable

A function or method saved as a fn value with foo(...) or $object->method(...).

Future

A read-only view of a value or throwable that will arrive later.

Identity

The rule by which two values refer to the same object or callable.

Interface

A set of methods, properties, constants, and constructor rules that an object must meet.

Literal type

A type that contains one scalar, constant, or enum-case value.

Newtype

A runtime tag placed on a value that must fit a backing type.

Nullable type

A union of null and another type, written null|T.

Partial function application

A call expression that creates a callable with selected arguments left open, such as foo(?, 'fixed').

Reified generic

A generic whose type arguments stay available while the program runs.

Resource

An object whose lifetime code checks with using or drop!.

Sealed family

A class or interface that lists the symbols allowed directly below it.

Strong reference

A reference that keeps an object alive.

Symbol

A named class, interface, enum, function, constant, alias, or newtype.

Task

A cooperatively scheduled async call.

Tuple

An immutable fixed-size array whose positions may have different types.

Type alias

A transparent name for another type.

Type identifier

An engine-local integer used to compare or index runtime types.

Unit enum

An enum whose cases have names but no backing values.

Value semantics

Assignment and argument passing give arrays independent values. The runtime may share their storage until one value changes.

Vec

A mutable dense array with uint keys from zero.

Weak reference

A reference that observes an object without keeping it alive.

Wildcard type

_ inside another type, meaning that a nested type exists but need not match one fixed type.