helix-dsl-macros

Procedural macros for the helix-dsl query registration system.

This crate provides the #[register] attribute macro, which transforms query-building functions into self-registering queries with compile-time parameter validation and runtime metadata.

Usage

use helix_db::prelude::*;

#[register]
fn find_user(username: String) -> ReadBatch {
    read_batch()
        .var_as("user", g().n_where(SourcePredicate::eq("username", username)))
        .returning(["user"])
}

#[register]
fn create_post(payload: ParamObject) -> WriteBatch {
    write_batch()
        .create_node("Post", payload)
}

The macro:

1. Strips parameters from the function signature and replaces them with let bindings to Expr::param(...), making them available as typed query expressions inside the body.
2. Generates a metadata function (__helix_dsl_params_{name}) that returns a Vec<QueryParameter> describing each parameter's name and type.
3. Registers the query via inventory as a RegisteredReadQuery or RegisteredWriteQuery, making it discoverable at runtime by helix_db::generate().

Supported parameter types

Nested arrays are supported (e.g. Vec<Vec<f64>> maps to Array(Array(F64))).

Constraints

The macro rejects functions that are:

• async
• Generic (type parameters)
• Methods (have a self receiver)
• Using destructuring patterns in parameters
• Returning anything other than ReadBatch or WriteBatch

License

Apache-2.0