Construct programs in Rust

A frontend lowers its program syntax to Program. A caller can construct the same located representation directly, then execute it through ProgramHost. Use this path when your tool already has a parser or a typed query builder.

A native binding in Rust

This constructs a program that saves its initial input under selected:

use zirql::{ExpressionKind, Located, Program, Statement};

let program: Program<(), (), ()> = Program::new(
    vec![Located::new(
        Statement::Bind {
            name: Located::new("selected".into(), 4..12),
            expression: Located::new(ExpressionKind::Input, 15..20),
        },
        0..21,
    )],
    0..21,
);

Constructing the program runs no host hooks. To execute it, call evaluate_program with a ProgramHost, its native input, mutable context, initial Bindings and the active Budget. The returned bindings retain the host’s value type. This example uses unit payload types because there are no stages, set operators or emitters in it.

evaluate_expression is the corresponding entry point for one expression. A nested host selector can call it with relative input while retaining the same context and budget.

Supply program operations

ProgramHost supplies the native value type, charged copying, stage execution, set combination, record construction and emitters. Keep domain handles tied to the context that owns them. Use evaluate_expression for an individual expression, including a nested selector with relative input and the same budget.

The host integration guide describes validation and ownership requirements. The program reference explains scope, statement order and emission behavior.