Versions

TCCL has two independent version numbers:

• the language version (1, 2, …) decides how source code compiles and runs, and is part of consensus;
• the tool version (tccl 0.3.0) is the release of the compiler, CLI, simulator and playground, following semantic versioning.

Language versions#

What version 2 adds#

• Records with named fields; enums with allowed transitions checked on every store.
• Roles, grant, revoke, only; automatic RoleGranted/RoleRevoked events.
• Interfaces, calls between contracts, with value, origin; re-entrancy always rejected; contract depth 8.
• Modules (use, module sections) and the standard library std.token, std.items, std.payments.
• upgrade() and the upgrade authority model.
• Built-ins mul_div, isqrt, pow, code_hash, is_contract, is_final; to_text of enums.
• payable accepted before or after the return type.
• Security: 16 MiB memory limit per transaction; copies and decoded storage values priced per allocation; xs[i] and len(xs) no longer copy local lists.
• Effects (what a contract can do) and access rules recorded in the program for wallets and explorers.

Compatibility of version 1 sources#

Every valid version 1 contract compiles as version 2, with identical functions, state and events, and runs with identical results, storage, events and payments. Two things can differ:

• fuel — only where the contract copies lists or large values (version 2 charges per allocation, and sometimes less because xs[i] no longer copies);
• names — none: the new words are contextual, so a version 1 contract using to, from, record or only as names still compiles.

A program compiled as version 2 runs under version 2 rules (memory limit, prices); its storage layout is the same as the version 1 program's.

Compatibility policy#

1. A language version, once deployed, is frozen: its compiler output, error messages, fuel prices and runtime behaviour never change, so every node can replay history.
2. Improvements and fixes that change observable behaviour ship as a new language version, activated for new deployments at a network activation height.
3. Contracts keep the language version they were deployed with. A contract moves to a newer version only through an explicit upgrade by its authority.
4. Encodings are append-only: new enum variants go at the end; new program sections are added only for new versions.
5. Standard modules are frozen per language version; their source hashes are recorded in each program.

Tool releases#

The full list of changes is in CHANGELOG.md. The plan for activating version 2 on The Coin — including versioned ABI and state, fuel, old contracts, historical replay, tests, activation and recovery — is in implant-the-coin-language.md.

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