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Section 35: Runtime Model and Execution Semantics

TECHSPEC-35 — Section 35 · Version 0.1 · Status: Initial Draft

Status: draft. This section is an Initial Draft (Section 57 is a Working Register). It describes intended or proposed behavior, not a finalized, implemented language rule. Do not treat examples here as normative.

1. Runtime Philosophy

The runtime defines how compiled programs execute.

The language must have consistent execution semantics regardless of the underlying operating system, hardware, or compilation target.

The runtime must not introduce hidden behavior that contradicts the language specification.

2. Execution Model

Every program must follow a defined execution lifecycle:

  1. Load the compiled program.
  2. Validate required runtime components.
  3. Initialize required modules.
  4. Establish permitted resources and capabilities.
  5. Execute the program entry point.
  6. Manage tasks and resources.
  7. Complete execution or report failure.
  8. Release resources and perform required cleanup.

Rules: - Execution order must follow defined language semantics. - Module initialization must have documented ordering. - Entry points must be explicitly declared. - Initialization failures must prevent dependent execution. - Cleanup must occur on normal termination and handled failure paths.

3. Runtime State

The runtime manages program execution state.

This includes: - Active function calls. - Local variables. - Module state. - Owned resources. - Active tasks. - Pending operations. - Error propagation. - Runtime permissions. - Contract evaluation state.

Rules: - Runtime state must respect type, ownership, and mutability rules. - State changes must follow declared effects. - Invalid state transitions must be rejected where detectable. - Runtime failures must not silently corrupt application state.

4. Execution Targets

The language must define its own semantics independently of its compilation targets.

Initial target: - Python runtime.

Potential future targets: - Native machine code. - WebAssembly. - Other managed runtimes.

Rules: - Target-specific behavior must not redefine source-language behavior. - Unsupported features must produce explicit compilation errors. - Numeric, string, collection, error, and concurrency semantics must remain consistent. - Runtime-specific limitations must be documented. - Code generation must preserve the source program's defined behavior.

5. Determinism and Reproducibility

The language should provide predictable execution where program behavior permits it.

Rules: - Pure operations must produce consistent results for identical inputs under identical language semantics. - External dependencies must be identifiable. - Randomness must use explicit random-number facilities. - Clock access must be explicit. - Concurrent execution order must not be assumed deterministic. - Environment-dependent behavior must be declared. - Reproducibility guarantees must identify their assumptions.

6. Runtime Contract Enforcement

The runtime must enforce contracts that cannot be established statically.

This includes: - Preconditions. - Postconditions. - Object invariants. - Runtime type constraints. - Resource constraints. - Permission checks.

Rules: - Failed mandatory contracts must produce explicit failures. - Contract evaluation must not be silently skipped. - Runtime contract checks must identify the violated condition. - A successful runtime check establishes only that the checked condition held at that execution point. - Runtime checks must not be reported as formal proofs.

7. Runtime Failures

The runtime must distinguish between:

  • Declared application errors.
  • Contract violations.
  • Type or invariant violations.
  • Resource exhaustion.
  • External system failures.
  • Internal runtime faults.
  • Unexpected termination.

Rules: - Failures must preserve relevant causes. - Unexpected failures must remain observable. - Recovery must not continue from invalid state. - Failure reports must distinguish known outcomes from uncertain outcomes. - Cleanup failures must not silently erase the original failure.

8. Runtime Resource Management

The runtime manages resources including: - Memory. - File handles. - Network connections. - Database connections. - Processes. - Tasks. - Timers.

Rules: - Resource ownership must follow the language's ownership model. - Resources must be released according to documented lifecycle rules. - Resource exhaustion must be observable. - Cleanup must not be assumed successful without evidence. - Resource limits must be configurable where appropriate.

9. Runtime Isolation and Security

The runtime must enforce the permissions declared by the program.

Rules: - Programs must not receive unrestricted system access by default. - External operations must pass through permission-controlled interfaces. - Dependencies must not automatically inherit unrestricted capabilities. - Runtime isolation guarantees must be documented. - Security boundaries must not be claimed stronger than the underlying platform supports.

10. Runtime and Verification Reporting

The runtime must provide structured execution evidence.

Reports should distinguish:

  • Program loaded.
  • Runtime initialized.
  • Execution started.
  • Contracts evaluated.
  • External operations attempted.
  • Execution completed.
  • Cleanup attempted.
  • Cleanup completed.
  • Unexpected failures encountered.

Execution success must not automatically imply program correctness.

11. Design Goal

An AI agent must be able to understand exactly how its program executes, which runtime guarantees apply, what failures occurred, and which properties remain unverified.

The runtime must enforce the language's rules rather than quietly relying on the behavior of its implementation platform.

Source file: TECHSPEC-35.md (preserved in source-original/LANG/). See the specification index, the glossary, and the cross-reference index.