046 capture existing struct

// Test: Capture from existing struct (no { } literal)
//
// ~capture(existing_var) binds to existing struct instead of creating new one
// captured { field: expr } updates just that field, preserves others
//
// Key: No { } in capture() → bind to existing variable

~import "$std/io"
~import "$std/control"

const std = @import("std");

const Entity = struct {
    id: u32,
    health: i32,
    pos_x: i32,
};

~event print_health { value: i32 }

~proc print_health {
    std.debug.print("{d}\n", .{value});
}

const entity = Entity{
    .id = 42,
    .health = 100,
    .pos_x = 10,
};

~capture(entity)
| as acc |> for(&[_]i32{10, 20, 30})
    | each damage |> captured { health: acc.health - damage }
| captured final |> print_health(value: final.health)