Type Constraints

Syntax

type <Name> = <BaseType>

command <Name> {
  <fieldName>: <TypeName>
}

Fields in commands, events, and state variants use name: TypeName syntax. The type name must reference a type declared within the same context.

context Registration {
  type UserId = String
  type Email = String

  command Register {
    userId: UserId
    email: Email
  }
}

The compiler resolves each field’s type against the declarations in the enclosing context. Resolution happens before any semantic analysis.

Type errors are reported with file, line, and column:

Unknown type 'EmailAddress' in command Register (field: email).
Declared types in context Registration: UserId, Email, DisplayName

Type declarations are scoped to the context in which they appear. A type declared in one context is not visible in another.