Attributes

Zirric supports annotating declarations with metadata via attributes. Attributes are processed
at compile time and can be accessed at runtime via reflection.

Syntax

Attributes are written as @Name(args...). Arguments are comma-separated
expressions, including literals, identifiers, or function literals.

@AttrName("argument", 123)
data MyData

Before being able to use an attribute, it must be declared and imported:

mod my

attr AttrName {
    field
    field2
}

// other module
import my

@my.AttrName
data SomeDeclaration

Syntactic sugar

If the attribute has no arguments, the parentheses can be omitted.

@AttrName
data MyData

If the referenced type is not an attribute, it will implicitly be converted to
an @Type attribute.

data MyData {
    @String // equivalent to @Type(String)
    field
}

Built-in attributes

The prelude defines common attributes used by the compiler, runtime, and tools:

  • @Type(T): declares a value or field to be of type T.
  • @Has(AttributeType): requires values to carry a specific attribute.
  • @Returns(T): declares a function return type.
  • @Default(value): documents a default value.
  • @Doc(text): attaches a documentation string.
  • @Deprecated(reason): marks a declaration as deprecated.
  • @Numeric: marks values that can be converted to numbers.

@Type

@Type specifies the type of a declaration. It is also used implicitly when
annotating with non-attribute types like @String.

data MyData {
    @Type(String)
    field
}

// or

data MyData {
    @Type("String")
    field
}
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