Array[T]

Array[T]

PyGo provides first-class support for generic array types using the Array[T] syntax. Arrays are type-safe at compile time and mechanically transpiled to idiomatic Go slices and Python lists.

Basic Usage

model Team:
  name: String
  members: Array[String]    # Array of strings
  scores: Array[Int]        # Array of integers

Nested Arrays

model Matrix:
  data: Array[Array[Float]]  # 2D array of floats

Arrays of Models

model User:
  name: String
  tags: Array[String]

model Project:
  title: String
  users: Array[User]  # Array of model instances

Type Safety

Arrays are validated at compile time:

team = Team(name="Alpha", members=["Alice", "Bob"])

# Valid — all elements are String
team.members = ["Alice", "Bob", "Charlie"]

# Invalid — the transpiler rejects this (Int is not String)
# team.members = ["Alice", 42]

Generated Code

Go:

type Team struct {
    Name    string
    Members []string
    Scores  []int
}

Python:

class Team(BaseModel):
    name: str
    members: list[str]
    scores: list[int]

Database Representation

Arrays are stored in the database based on the backend:

• PostgreSQL: Native ARRAY type
• SQLite: JSON-encoded array

-- SQLite (JSON-encoded)
CREATE TABLE team (
    id INTEGER PRIMARY KEY,
    name TEXT NOT NULL,
    members TEXT,    -- JSON: ["Alice", "Bob", "Charlie"]
    scores TEXT      -- JSON: [10, 20, 30]
);

Array Operations

PyGo provides a set of operations that work on arrays in both Go and Python:

Append

team.members.append("David")

Extend

team.members.extend(["Eve", "Frank"])

Filter (in handler)

handler listActiveUsers:
  list(team_id: UUID) -> Array[User]:
    team = Team.find(team_id)
    return team.members.filter(active=True)

Length

count = len(team.members)

Nullable Arrays

Use Array[T]? for nullable arrays:

model Team:
  name: String
  members: Array[String]? = None  # Can be NULL

Best Practices

• Use Array[String] for homogeneous string collections
• Use Array[Model] for embedded model references
• Avoid arrays of arrays for better database compatibility
• Use Array[String]? for optional arrays (can be NULL)