028 capture multi

// Test: ~capture with multiple accumulated fields
//
// This demonstrates the power of struct accumulators:
// - One pass through the data
// - Multiple values captured simultaneously
// - Pure semantics (compute entire next state at once)
// - Efficient generated code
//
// Compare to Haskell:
//   fold (\(sum, max) x -> (sum + x, max `max` x)) (0, -inf) items
//
// Koru is MORE READABLE with the same purity guarantees!

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

~event compute_stats {}
| result { sum: i32, max: i32 }

// Compute sum and max in one pass
// Values: 3, 1, 4, 1, 5 -> sum=14, max=5
~compute_stats = capture(init: { sum: @as(i32, 0), max: @as(i32, 0) })
| as c |>
  for(&[_]i32{ 3, 1, 4, 1, 5 })
  | each val |> captured {
      sum: c.sum + val,
      max: if (val > c.max) val else c.max
    }
| captured final |> result { sum: final.sum, max: final.max }

~compute_stats()
| result _ |> std.io:println(text: "done")