015 abstract impl

// Abstract events: `~[abstract]` declares a signature; a `~proc` in the same
// file is an optional default implementation; `~module:event = ...` provides
// THE implementation. Within an implementation, calling the event name
// delegates to the default. Resolved at compile time — no runtime dispatch.

const std = @import("std");

// Example 1: Abstract event WITH default implementation
// The default can be called from within implementation via delegation
~[abstract] tor coordinate { ctx: i32 } -> i32

~proc coordinate|zig {
    std.debug.print("Default coordination: {}\n", .{ctx});
    return ctx;
}

// Example 2: Abstract event WITHOUT default implementation
// User MUST provide implementation or compile error
~[abstract] tor process { data: i32 } -> i32

// Helper proc for Example 4
~tor double { value: i32 } -> i32

~proc double|zig {
    return value * 2;
}

// Example 3: Implementation that delegates to default and extends
// The module qualifier (input:) marks this as an impl override
// Module name is derived from filename: input.kz -> "input"
~input:coordinate =
    coordinate(ctx: 42)  // Delegates to default
    | finished f -> f + 1

// Example 4: Implementation that provides complete logic
// No delegation to default (there isn't one for 'process')
~input:process =
    double(value: data)
    | result r -> r

// Use the implemented events
~coordinate(ctx: 10)

~process(data: 5)