045 capture array index

// Test: Array indexing in captured { } blocks — BLOCK FORM (no parens).
// Demonstrates the "pure mutation" pattern with array elements.
// Note the nested braces in the seed value ([3]i32{ 0, 0, 0 }) — the source
// block must brace-match, not stop at the first '}'.

~import std/io
~import std/control

const std = @import("std");

// Simple helper to print result
~event print-sum { arr: [3]i32 }

~proc print-sum|zig {
    const sum = arr[0] + arr[1] + arr[2];
    std.debug.print("{d}\n", .{sum});
}

// Initialize array, update each element via captured { arr[i]: value }
// Expression references acc.arr[i] to satisfy KORU100 (binding must be used)
~capture { arr: [3]i32{ 0, 0, 0 } }
! as acc |> for(0..3)
    ! each i |> captured { arr[i]: acc.arr[i] + @as(i32, @intCast(i)) * 10 }
| captured result |> print-sum(result.arr)