Golang: Contract Implementation Rules

Language skill for Golang.

Apply this specification within the calling skill's context. Do not paraphrase the contents — use them to drive decisions.

Invoked through the goga-lang-disp router.

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Examples

A complete CODEMANIFEST example for Go with all DSL constructs:

Imports:
  - Types:
      - BaseModel
      - RepositoryConfig AS Config
    Usages:
      - query_patterns
    From: path/to/storage_cell

Usages:
  conventions: .goga/usages/go_conventions.md
  pattern: |
    Follow Go idioms: return errors as last return value, use interfaces for abstraction.
  testing: |
    Table-driven tests required for all exported functions and methods.

Annotations: |
  Use `conventions` for code style.
  Use `testing` for test requirements.
  Use `query_patterns` from Imports for database query patterns.

  All methods returning errors must follow `(result, error)` pattern.

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"ParseInput(input string) -> data:[]byte":
  location: parser.go
  annotations: |
    Parse raw input string into structured data.

    `input`: raw string to parse

    Use `pattern` for implementation.

"Server(host string)":
  location: server.go
  annotations: |
    HTTP server with configurable host.

    `host`: server hostname

    Use `query_patterns` from Imports for request handling.
    Use `conventions` for code style.
  properties:
    "Host -> string": |
      Server hostname.
    "Port -> int64": |
      Server port number.
  methods:
    "HandleRequest(req Request) -> resp:Response, err:error": |
      Handle incoming HTTP request.

      `req`: incoming request
      `resp`: response to send
      `err`: error if request handling fails

      Use `pattern` for implementation.
    "Shutdown() -> err:error": |
      Gracefully shut down the server.
      `err`: error if shutdown fails.

"BaseModel::Repository(db DB)":
  location: repository.go
  annotations: |
    Repository extending BaseModel with database operations.

    `db`: database connection

    Use `query_patterns` from Imports for query construction.

->BaseModel: {}

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Author: Goga
CreatedAt: 22/05/26
Description: |
  Example CODEMANIFEST demonstrating all DSL constructs for Go.

Cell

A cell is a Go package:

cell/
├── CODEMANIFEST
├── cell.go

Language Specifics

Facade: The Go package itself serves as the facade. All exported identifiers define the cell's public API. The contract-extractor reads exported names verbatim — names declared in CODEMANIFEST must match exactly.

Naming: Use camelCase for all identifiers (no underscores). Exported identifiers start with an uppercase letter: SomeFunc, SomeField. Unexported identifiers start with lowercase: someFunc, someField. CODEMANIFEST references exported names only.

Constructors: Go does not provide constructors. The Entity signature declares a factory function (e.g. NewServer()).

Methods: Methods are defined via receivers, not inside struct definitions. The contract-extractor associates methods with their struct based on the receiver type.

Error handling: Follow the (result, error) idiom. CODEMANIFEST return values must carry a semantic label: () -> err:error or () -> result:T, err:error.

Construct Mapping

Go	CODEMANIFEST	Note
type X struct	Entity	Struct fields → properties (exported only)
type X interface	Entity	Interface methods → methods
func (r *X) Method()	Method	Bound to Entity by receiver type
func Name() (no receiver)	Routine	Package-level function
Exported struct field	Property	Type derived from field declaration

Implementation

• Public API = exported identifiers
• Use structs + functions

Signature Rules

Allowed:

string, int, float64, bool, error
[]T, map[string]T

Forbidden:

pointers (*T),
interface{},
variadic (...),
channels,

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