Spec-ID: x07.spec.internal.types.type-system-v1@0.1.0 Status: draft Applies-to: toolchain >= v0.0.95 Related schemas: []

Type System v1 (Phase H1)

Phase H1 introduces a small, explicit set of concrete types with ABI-stable layouts.

Where types appear

• defn decl objects: {"kind":"defn","name":"main.f","params":[{"name":"arg1","ty":"ty1"}],"result":"ret_ty","body":<expr>}
• defasync decl objects (Phase G2): {"kind":"defasync","name":"main.f","params":[{"name":"arg1","ty":"ty1"}],"result":"bytes","body":<expr>}
  • defasync return type is currently restricted to bytes.

In the v1 monomorphic ABI subset, type names are identifiers.

As of x07.x07ast@0.4.0, signature types are type_ref (string or structured type expression), and defn/defasync may declare type_params for compile-time monomorphized generics.

Supported types

• i32: 32-bit integer (used for arithmetic, indices, booleans-as-0/1, and error codes)
• bytes: owned byte buffer (ptr + len, dropped automatically)
• bytes_view: borrowed byte view (ptr + len + debug-only borrow tracking fields)
• vec_u8: owned, growable byte vector value (data + len + cap, dropped automatically)
• option_i32, option_bytes, option_bytes_view: tagged options (Phase H1)
• result_i32, result_bytes, result_bytes_view, result_result_bytes: tagged results with deterministic error codes (Phase H1)
• iface: interface record (data + vtable) used for streaming readers (Phase H1/G2)
• Raw pointers (Phase H4, standalone-only): ptr_const_u8, ptr_mut_u8, ptr_const_void, ptr_mut_void, ptr_const_i32, ptr_mut_i32

Branded bytes

Bytes-like types may carry an optional compile-time brand:

• params: {"name":"x","ty":"bytes","brand":"my.encoding_v1"}
• return values: {"result":"bytes","result_brand":"my.encoding_v1", ...}

Brands exist only in typing and are erased during lowering (no runtime representation changes).

ABI and lowering

The C ABI for these types is defined by:

• docs/spec/abi/abi-v2.md
• crates/x07c/include/x07_abi_v2.h

iface is specified under docs/spec/abi/interface-records-v1.md.

Phase H1 builtins (typed)

• Options: option_i32.*, option_bytes.*
• Results: result_i32.*, result_bytes.*
• Propagation: ["try", r]
  • try is only valid inside a defn whose return type is result_i32 or result_bytes.