043 const basic

// Test: the const/capture PAIR — the two sibling source-block forms composed.
// `~const { ... }` declares the immutable config (flat per-target declaration,
// names used directly); `~capture { ... }` declares the mutable cell. Same
// argument shape (one source block), opposite mutability. Migrated 2026-06-11
// from three generations of dead surface (`~const({...})` parens + `| as cfg`
// + `=>` branch bodies); the old form pinned the nested-capture-in-const gap,
// which dissolved when both forms went flat.
// sum = (6 + 8 + 10) * 2 = 48 over threshold 5.

~import std/io
~import std/control

~const { threshold: @as(i32, 5), multiplier: @as(i32, 2) }

~capture { sum: @as(i64, 0), count: @as(i32, 0) }
! as acc |> for(&[_]i32{1, 3, 6, 8, 10})
    ! each item |> if(item > threshold)
        | then |> captured { sum: acc.sum + @as(i64, item) * multiplier, count: acc.count + 1 }
        | else |> captured { acc.sum, acc.count }
| captured result |> std/io:print.ln("{{ result.sum:d }}")