Syntax & x07AST (JSON)

X07 uses a structured syntax called x07AST.

• Humans can work with a pretty form.
• Agents should operate directly on the JSON AST (no fragile text edits).

Why JSON AST?

Text-based syntaxes (even simple ones) often fail under autonomous patching:

• parentheses drift
• braces drift
• indentation drift
• accidental truncation

A JSON AST:

• is easy to validate,
• is easy to patch with JSON Patch,
• is easy to autoformat deterministically,
• makes tooling (lint/repair) reliable.

Core expression model

x07AST is an expression tree:

• lists: ["head", arg1, arg2, ...]
• identifiers: "std.bytes.len" (string)
• integers: 123 (number)

The entrypoint expression returns bytes.

Tooling

• x07 ast init / x07 ast validate:
  • generates and validates *.x07.json skeletons
• x07c fmt:
  • canonicalizes JSON (JCS) and ensures stable emission
• x07c lint:
  • checks schema + semantic constraints
  • prints x07diag (machine-readable diagnostics)
• x07c fix:
  • applies quickfixes (JSON Patch) and rewrites *.x07.json deterministically

Common mistakes (and the canonical fixes)

1) Using multi-step logic where a single expression is required

Fix: wrap with ["begin", ...].

2) Returning the wrong type from the entrypoint

Fix: ensure the final expression is bytes.

3) Calling OS-only builtins in fixture worlds

Fix: keep OS builtins behind OS adapters and world checks.