Type Aliases

Overview

Echo supports named aliases for built-in types and object-shaped aliases for hashes.

Syntax

type Age = int;
type User = { id: int, name: str, active: bool };

Example

type User = { id: int, name: str, active: bool };

user: User = {
    id: 1,
    name: "Echo",
    active: true
};

say(user);

Output

{"id": 1, "name": "Echo", "active": true}

Notes

• Aliases can be used in variable declarations and function parameters.
• Object aliases check that required fields exist and match declared field types.
• Built-in type names cannot be redefined.
• Alias names cannot be redefined.

Common Mistakes

• Assuming object aliases reject extra fields
• Treating aliases as new runtime types

Current Limitation

Object aliases validate required fields but do not reject additional fields.

See Also

• Variables and Types
• Functions
• Hashes