Core Language Specification v0.1

Core Language Specification v0.1

Canonical source: spec/PROTOS_LANGUAGE_SPEC.md at locked revision e99b712ecf658a527b1fe82c8beba2c1286d8dc9. The source document’s own status and authority declarations apply; this website rendering does not upgrade, downgrade, or redefine them.

Language version: 0.1 Status: Draft Last updated: 2026-09-11 Normative I/O-domain semantics are defined in io/IO_CORE.md.

Normative semantic-domain ownership is modularized under semantics/: OBJECT_MODEL.md, EXECUTION_AND_CONTROL.md, CALLABLES.md, MODULES.md, ERRORS.md, VALUES_AND_COLLECTIONS.md, and MATCHING.md. Compatibility headings retained in this document are navigation only.

Normative concurrency-domain semantics are defined by the modular specifications under concurrency/. Non-normative unresolved concurrency design notes live in ../docs/design/CONCURRENCY_DESIGN.md and are not a source of observable behavior.

Language Name

The language defined by this specification is named Protos.

1. Principles

The language is an object-oriented language based exclusively on prototypes and delegation.

There are no classes.

Every observable value is an object. This includes numbers, strings, booleans, closures, errors, futures, execution contexts, and null.

An implementation may internally represent some objects using immediate values, tagged pointers, specialized memory layouts, or other optimizations, provided that these optimizations are not observable through the language semantics.

The language has a uniform execution model. There is no fundamental semantic distinction between “global code”, “local variables”, and “properties”. Execution always takes place within contexts, and contexts are themselves objects.

The language favors objects and messages over keywords and special syntactic constructs.

Core v0.1 does not provide arbitrary custom symbolic binary operators. The accepted symbolic source surface and its precedence are fixed by PROTOS_GRAMMAR.md. Ordinary named messages/calls remain the extensibility mechanism for user-defined behavior, and Object.alias does not create new source-level operator spellings.

1.1 Identifier Syntax and Reserved Words

The primary normative owner of identifier lexing, Unicode/NFC requirements, reserved words, and contextual member-name syntax is PROTOS_GRAMMAR.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

1.2 Dynamic Typing

Core v0.1 is dynamically typed.

Slots and parameters do not carry mandatory static type declarations. A slot may hold objects with different behavior over time, subject only to the normal object-state and assignment rules.

Message validity is determined dynamically by receiver behavior and delegation. The language does not introduce overload resolution by declared argument type.

Implementations and tools may infer types, specialize code, or expose optional analysis, but such information must not change observable language semantics.

2. Objects

The primary normative contract formerly contained here has moved to semantics/OBJECT_MODEL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

3. Slot Creation and Modification

The primary normative contract formerly contained here has moved to semantics/OBJECT_MODEL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

4. Execution Context

The primary normative contract formerly contained here has moved to semantics/EXECUTION_AND_CONTROL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

Module Contexts and Top-Level Bindings

The primary normative contract formerly contained here has moved to semantics/MODULES.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

5. this

The primary normative contract formerly contained here has moved to semantics/EXECUTION_AND_CONTROL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

6. Unqualified Lookup

The primary normative contract formerly contained here has moved to semantics/EXECUTION_AND_CONTROL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

7. Unqualified Assignment

The primary normative contract formerly contained here has moved to semantics/EXECUTION_AND_CONTROL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

8. super

The primary normative contract formerly contained here has moved to semantics/EXECUTION_AND_CONTROL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

8.1 Evaluation Order

The primary normative contract formerly contained here has moved to semantics/EXECUTION_AND_CONTROL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

9. Closures

Closure syntax and mandatory syntactic desugaring are owned by PROTOS_GRAMMAR.md. Closure value/capture/invocation semantics are owned by semantics/CALLABLES.md. This heading is a compatibility/navigation anchor and is not an independent normative owner.

10. Closures and Methods

The primary normative contract formerly contained here has moved to semantics/CALLABLES.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

11. Extracted Methods

The primary normative contract formerly contained here has moved to semantics/CALLABLES.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

12. Closures and super

The primary normative contract formerly contained here has moved to semantics/CALLABLES.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

13. Return Semantics

The primary normative contract formerly contained here has moved to semantics/CALLABLES.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

14. Return from Escaped Closures

The primary normative contract formerly contained here has moved to semantics/CALLABLES.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

15. null

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

16. Booleans

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

17. Iteration and Loops

The primary normative contract formerly contained here has moved to semantics/EXECUTION_AND_CONTROL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

18. Trailing Closures

Trailing-closure syntax, attachment, and mandatory desugaring are owned by PROTOS_GRAMMAR.md; the resulting Closure obeys semantics/CALLABLES.md. This heading is a compatibility/navigation anchor and is not an independent normative owner.

19. Separators, Line Breaks, and Comments

The primary normative owner of whitespace, comments, NEWLINE tokens, separators, and continuation grammar is PROTOS_GRAMMAR.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

20. Object Composition

The primary normative contract formerly contained here has moved to semantics/OBJECT_MODEL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

21. Equality and Identity

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

21.1 Fixed Symbolic Operator Surface

The accepted symbolic source spellings, precedence, associativity, and lexical rejection rules are owned by PROTOS_GRAMMAR.md. Arbitrary custom symbolic binary operators are not part of Core v0.1. This heading is a compatibility/navigation anchor and is not an independent normative owner.

22. Open Objects

The primary normative contract formerly contained here has moved to semantics/OBJECT_MODEL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

23. Closed Objects

The primary normative contract formerly contained here has moved to semantics/OBJECT_MODEL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

24. Frozen Objects

The primary normative contract formerly contained here has moved to semantics/OBJECT_MODEL.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

25. Errors

The primary normative contract formerly contained here has moved to semantics/ERRORS.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

26. Futures

The normative contract formerly contained in this section has moved to concurrency/FUTURES_AND_TASKS.md. This heading remains as a compatibility/navigation anchor; it defines no independent duplicate contract.

27. Asynchronous Execution

The normative contract formerly contained in this section has moved to concurrency/FUTURES_AND_TASKS.md. This heading remains as a compatibility/navigation anchor; it defines no independent duplicate contract.

28. Future State, Resolution, Failure, and Adoption

The normative contract formerly contained in this section has moved to concurrency/FUTURES_AND_TASKS.md. This heading remains as a compatibility/navigation anchor; it defines no independent duplicate contract.

29. Obtaining a Future’s Value

The normative contract formerly contained in this section has moved to concurrency/FUTURES_AND_TASKS.md. This heading remains as a compatibility/navigation anchor; it defines no independent duplicate contract.

30. Future Composition

The normative contract formerly contained in this section has moved to concurrency/FUTURES_AND_TASKS.md. This heading remains as a compatibility/navigation anchor; it defines no independent duplicate contract.

31. Structured Concurrency

The normative contract formerly contained in this section has moved to concurrency/FUTURES_AND_TASKS.md. This heading remains as a compatibility/navigation anchor; it defines no independent duplicate contract.

32. Primitives

Expressing an operation through messages does not require its entire implementation to be written in the language.

For example, arithmetic messages may ultimately execute native arithmetic primitives.

Likewise:

closure.future()

may ultimately invoke a scheduler primitive.

A primitive is an implementation mechanism, not an exception to the object model.

33. Constructs Outside the Semantic Core

The core does not require these as semantic primitives:

class
extends
new

var
let
const

function

async
await

for

undefined

try
catch
throw
finally

if and else remain ordinary identifiers in Core v0.1 and have no dedicated conditional syntax; if(condition) { ... } retains its ordinary call-plus-trailing-Closure grammar rather than being reserved for conditional reinterpretation. Canonical conditional execution is the ordinary Boolean protocol owned by semantics/VALUES_AND_COLLECTIONS.md and its surface grammar boundary is owned by PROTOS_GRAMMAR.md.

return and while remain independent possible future syntactic-sugar questions.

34. Core Language Invariants

Everything is an object.

The language is dynamically typed.

There are no classes.

Object is the unique root object and has no delegation parent.

Every other object has exactly one delegation parent.

Every delegation chain terminates at Object.

Every object may serve as a delegation parent.

An object's delegation parent cannot change after creation.

Reads may delegate.

Writes never delegate.

: creates.
= modifies.

null is the only absence value.

A missing slot is not null; it is an error.

Execution contexts are objects; their standard prototype is `Context`.

Closures capture lexical contexts by reference.

Methods dynamically receive their receiver.

Inner closures capture that receiver.

Extracted methods remain bound to their receiver.

super preserves both the receiver and the lookup origin.

^ performs a non-local return.

Errors are objects and are signaled.

Futures are objects.

Asynchrony is a property of an execution,
not a separate category of function.

Objects may be closed or frozen.

Horizontal composition does not modify the delegation chain.

Top-level bindings are slots of a module execution context.

There is no special global-variable category.

Modules do not implicitly share mutable global state.

Actors share no mutable Protos state; any Protos object physically shared between Actors through the standard prelude is semantically immutable for the duration of that sharing.

Conditional Protocol and Truthiness

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Error Signaling and Handling

The primary normative owner of Core Error signaling, dynamic handlers, matching, unwinding, and non-resumable failure semantics is semantics/ERRORS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Module Loading, Identity, and Cycles

The primary normative contract formerly contained here has moved to semantics/MODULES.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

Indexed Access Syntax

Indexed-expression grammar and mandatory lowering are owned by PROTOS_GRAMMAR.md; standard collection at/atPut behavior is owned by semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Standard Array Indexed Semantics

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility and navigation anchor; it is not a second normative owner.

Standard Array Parallel Operations

Core defines no parallel Array operations; parallel Array algorithms are Standard Library functions of std:collections/Array. The Core placement boundary is owned by concurrency/PARALLEL_EXECUTION.md §71.6. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Invocation Arguments, Defaults, Rest, and Spread

The primary normative contract formerly contained here has moved to semantics/CALLABLES.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Polymorphic Invocation and Object Construction

The primary normative contract formerly contained here has moved to semantics/CALLABLES.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Contextual Meaning of ...

The primary normative owner of the context-sensitive grammar and mandatory lowering of ... is PROTOS_GRAMMAR.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Resource Cleanup and ensure

The primary normative contract formerly contained here has moved to semantics/EXECUTION_AND_CONTROL.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Numeric Equality Across Families

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Float Special Values and Identity

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Float Signed Zero Semantics

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Parameter Name Uniqueness

The primary normative contract formerly contained here has moved to PROTOS_GRAMMAR.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Numeric Model

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Text, Bytes, and Character Encodings

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Prefix Operators and Protocol-Based Negation

The primary normative owner of prefix-operator syntax and mandatory message-send lowering is PROTOS_GRAMMAR.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

String Literal Semantics

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

String Indexing, Mutability, and Encoded Representations

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Maps, Hashing, and Key Equality

The primary normative contract formerly contained here has moved to semantics/VALUES_AND_COLLECTIONS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Future Cancellation

The primary normative owner of Future cancellation state, cancel(), cancellation boundaries, unwind effects, and cancelled-result observation is concurrency/FUTURES_AND_TASKS.md; standard Error construction/category semantics are owned by semantics/ERRORS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Future Failure and Dynamic Error Context

The primary normative owner of Future failure recording, observation, and dynamic-handler boundaries is concurrency/FUTURES_AND_TASKS.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Concurrency Memory Semantics

The primary normative owner of the applicable Actor-local task, Actor-isolation, completion-visibility, and isolated-P boundary contracts is concurrency/FUTURES_AND_TASKS.md, concurrency/ACTORS.md, and concurrency/PARALLEL_EXECUTION.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.

Core Reflection

The primary normative contract formerly contained here has moved to semantics/OBJECT_MODEL.md. This heading remains as a compatibility/navigation anchor and is not an independent normative owner.