Derive Macro PartialType 

#[derive(PartialType)]
{
    // Attributes available to this derive:
    #[partial]
}

Derives a partial type for streaming support.

Generates a Partial{TypeName} struct with all fields wrapped in Option<T>. The partial type is useful for progressive emission during streaming responses, where not all fields may be available yet.

Generated Code

For each struct annotated with #[derive(PartialType)], this macro generates:

1. Partial Struct: Partial{TypeName} with all fields as Option<T>

   • Derives: Debug, Clone, Default, Serialize, Deserialize

2. Conversion Method: from_partial() on the original type

   • Converts PartialType → Type
   • Returns Result<Type, String> (error if required fields missing)

3. Merge Method: merge() on the partial type

   • Merges two partial values (newer values take precedence)

Field Attributes

• #[partial(skip)] - Exclude field from partial type (always uses default)
• #[partial(default)] - Use default value if missing in partial

Example

use simple_agents_macros::PartialType;
use std::time::Duration;

#[derive(PartialType)]
pub struct Resume {
    pub name: String,
    pub email: String,
    #[partial(default)]
    pub skills: Vec<String>,
    #[partial(skip)]
    pub created_at: Duration,
}

let mut partial = PartialResume::default();
partial.name = Some("Alice".to_string());
assert_eq!(partial.email, None);

partial.merge(PartialResume {
    email: Some("alice@example.com".to_string()),
    skills: Some(vec!["Rust".to_string()]),
    ..Default::default()
});

let resume = Resume::from_partial(partial).unwrap();
assert_eq!(resume.name, "Alice");
assert_eq!(resume.skills, vec!["Rust".to_string()]);

Streaming Annotations

Future versions will support streaming annotations:

• #[partial(stream_not_null)] - Don’t emit until non-null
• #[partial(stream_done)] - Only emit when complete