1 files changed, 43 insertions, 0 deletions
diff --git a/lang/zig/while-unpack.zig b/lang/zig/while-unpack.zig
new file mode 100644
index 0000000..d10c385
--- /dev/null
+++ b/lang/zig/while-unpack.zig
@@ -0,0 +1,43 @@
+const expect = @import("std").testing.expect;
+
+var numbers_left: u32 = undefined;
+
+fn eventuallyNullSequence() ?u32 {
+    return if (numbers_left == 0) null else blk: {
+        numbers_left -= 1;
+        break :blk numbers_left;
+    };
+}
+
+fn eventuallyErrorSequence() anyerror!u32 {
+    return if (numbers_left == 0) error.ReachedZero else blk: {
+        numbers_left -= 1;
+        break :blk numbers_left;
+    };
+}
+
+test "while null capture" {
+    var sum1: u32 = 0;
+    numbers_left = 3;
+    while (eventuallyNullSequence()) |value|
+        sum1 += value;
+    expect(sum1 == 3);
+
+    var sum2: u32 = 0;
+    numbers_left = 3;
+    while (eventuallyNullSequence()) |value| {
+        sum2 += value;
+    } else {
+        expect(sum2 == 3);
+    }
+}
+
+test "while error union capture" {
+    var sum: u32 = 0;
+    numbers_left = 3;
+    while (eventuallyErrorSequence()) |value| {
+        sum += value;
+    } else |err| {
+        expect(err == error.ReachedZero);
+    }
+}