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Version: 0.1.13

FAQ

Is X07 a general-purpose language?​

Yes—via OS worlds it targets general-purpose usage (CLI tools, servers, automation).

Fixture worlds exist to make testing and repair deterministic, not to limit real-world capability.

Why not just use Rust / Go / Python?​

You can. X07 exists because autonomous agents struggle with:

  • multiple equivalent patterns,
  • ambiguous diagnostics,
  • nondeterministic test environments,
  • text-based patching on fragile syntax.

X07 makes those constraints first-class.

Is X07 safe?​

In deterministic worlds, X07 is designed to be safe-by-construction. In OS worlds, safety depends on policies and host sandboxing.

Is X07 fast?​

X07 compiles to C and can call native shims for performance-critical workloads.

The main performance risk is agent-written O(n²) logic—so the ecosystem includes budgets, metrics, and canonical builders.

What is the canonical way to do streaming transforms?​

Use Streaming pipes (std.stream.pipe_v1): they are deterministic, budgeted, and have a single canonical composition model (source → transducers → sink).

How do I make OS-world behavior reproducible for agents?​

Use Record/replay (std.rr) to record real interactions into cassettes under .x07_rr/, then replay deterministically in solve-rr.

How do I prevent “agent refactor” performance regressions?​

Use Budget scopes to localize resource contracts, and enforce repo-wide invariants with x07 arch check.

How do I run property-based tests?​

Use the built-in test harness:

  • x07 test --pbt --manifest tests/tests.json (property-based tests only)
  • x07 test --all --manifest tests/tests.json (unit + property-based)

When a counterexample is found, convert it into a deterministic regression test:

  • x07 fix --from-pbt <path/to/repro.json> --write

See: Property-based testing.

How do I use function contracts and verification?​

x07AST v0.5 supports requires / ensures / invariant on defn/defasync declarations.

  • Runtime contract violations show up in x07 test reports as failure_kind: "contract_violation" with a repro artifact path.
  • For bounded proof artifacts, run x07 verify --bmc|--smt --entry <sym> (subset supported in v0.1; see CLI docs).

See: Syntax & x07AST and CLI.

How do humans review agent patches?​

Use the toolchain’s semantic diff + trust report artifacts:

  • x07 review diff (intent-level HTML diff)
  • x07 trust report (budgets, worlds, nondeterminism summary)

See: Review & trust artifacts.

How do I integrate multiple subsystems (pipes + RR + budgets + contracts)?​

Start from the readiness-check examples under docs/examples/ — they combine real subsystems end-to-end. For the common patterns that trip up agents (bytes/view friction, assertion ownership, fixture paths), see Agent patterns.

Why does my bytes.view fail with "requires an identifier"?​

bytes.view takes a named local, not an arbitrary expression. Bind the bytes-producing expression to a local first:

["let", "raw", ["bytes.lit", "hello"]],
["bytes.view", "raw"]

See Agent patterns — bytes vs bytes_view for the full set of ownership recipes.

What does x07 doc std.stream.pipe_v1 return?​

x07 doc std.stream.pipe_v1 prints built-in documentation for the special form, including its shape and a short example.

Use x07 guide and Streaming pipes for the complete reference and composition guidance.