060 tap as library

// Test: Taps implemented as a library transform
// This proves taps don't need special syntax - they're just metaprogramming!

const std = @import("std");
~import std/taps

// An event with an identity branch that can be tapped.
// Taps work by observing TRANSITIONS (branches), not void events!
~event hello {}
| greeted []const u8

~proc hello|zig {
    std.debug.print("Hello executed\n", .{});
    return .{ .greeted = "go" };
}

// A void observer event - no return needed
~event observer {}

~proc observer|zig {
    std.debug.print("Observer fired!\n", .{});
}

// TAP: Observe hello -> * | greeted
// Using the library syntax instead of a special form
~tap(hello -> *)
| greeted _ |> observer()

// Execute hello - tap should fire on the greeted branch
~hello()
| greeted _ |> _