Kotlin: Contract Implementation Rules

Language skill for Kotlin.

Apply this specification within the context of the calling skill. Do not restate the content — use it for making decisions.

Invoked via the goga-lang-disp router.

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Examples

Complete CODEMANIFEST example for Kotlin demonstrating all DSL constructs:

Imports:
  - Types:
      - UserModel
      - CacheConfig AS Config
    Usages:
      - caching
    From: path/to/cache_cell

Usages:
  conventions: .goga/usages/kotlin_conventions.md
  pattern: |
    Use data classes for models. Prefer immutable collections (List, Map) over mutable ones.
  testing: |
    Use JUnit 5. Each public method must have at least one test case.

Annotations: |
  Use `conventions` for code style.
  Use `testing` for test requirements.
  Use `caching` from Imports for cache invalidation patterns.

  Use `val` for all properties. Avoid `var` unless mutation is required by contract.

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"calculateTotal(a: Int, b: Int) -> total: Int":
  location: calculator.kt
  annotations: |
    Calculate the sum of two integers.

    `a`: first operand
    `b`: second operand

    Use `pattern` for implementation.

"UserRepository(config: Config)":
  location: repository.kt
  annotations: |
    Repository for user data access with caching.

    `config`: repository configuration from `Config` type.

    Use `caching` from Imports for cache strategy.
    Use `conventions` for code style.
  properties:
    "tableName -> String": |
      Database table name for users.
    "cacheSize -> Int": |
      Maximum number of cached entries.
  methods:
    "findById(userId: String) -> user: UserModel?": |
      Find a user by ID.

      `userId`: unique user identifier
      `user`: found user or null

      Use `caching` from Imports for cache lookup.
    "deleteById(userId: String)": |
      Delete user by ID.

      `userId`: unique user identifier

"UserModel::AdminUser(userId: String)":
  location: admin.kt
  annotations: |
    Admin user extending UserModel with elevated permissions.

    `userId`: unique user identifier

    Use `caching` from Imports for permission cache.

->UserModel: {}

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

Cell

A cell is a package/module:

cell/
├── CODEMANIFEST
├── *.kt

Language Features

Facade: all public classes and top-level functions in the package define the facade. Private and internal declarations are not part of the contract.

Naming: camelCase for functions and properties, PascalCase for classes.

Constructors: Entity signature describes the primary constructor. Constructor parameters are the input data for obtaining an instance.

Nullability: T? — nullable, T — non-null. CODEMANIFEST represents these directly via T? and T.

Construct Mapping

Kotlin	CODEMANIFEST	Note
class / data class (public)	Entity	Primary constructor → Entity signature
Top-level fun	Routine	Public function at file level
val / var class property	Property	Type from declaration
Class method fun	Method

Implementation

• Public classes and functions
• Use immutable types when possible

Signature Rules

Allowed:

String, Int, Double, Boolean
List<T>, Map<String, T>
T?

Forbidden:

Any
vararg
untyped collections

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