# V3010 invalid_operation_row

URL: /docs/errors/V3010
Markdown: /docs/errors/V3010.md

> An effect operation's row may contain only Fail<…> in v0 (design §5.5).

An error from the `effect` phase. `sakura explain V3010` prints this explanation offline.

An effect operation's row may contain only `Fail<…>` in v0 (design §5.5). An operation states
how it can fail; which other effects run is the handler's business, and the handler's own row
carries them.

Wrong:

```sakura
effect Store { fn save(key: String) -> Unit ! {Console} }
```

Fixed:

```sakura
error Full
effect Store { fn save(key: String) -> Unit ! {Fail<Full>} }
```

## Wrong program [#wrong-program]

[`compiler/tests/ui/V3010_invalid_operation_row.sakura`](https://github.com/icantcodefyi/sakuralang/blob/master/compiler/tests/ui/V3010_invalid_operation_row.sakura), which the compiler's ui suite runs through `sakura check`:

```sakura
effect Store {
  fn save(key: String) -> Unit ! {Console}
}
```

`sakura check --json` reports this record (pretty-printed; `$DIR` is the fixture's directory):

```json
{
  "schema_version": "1.0",
  "kind": "diagnostic",
  "id": "d:a4b7790be692f83a",
  "code": "V3010",
  "severity": "error",
  "phase": "effect",
  "message": "operation `save` may only declare `Fail<…>` in its row (design §5.5)",
  "snapshot": "sha256:$SNAPSHOT",
  "symbol_id": "main::V3010_invalid_operation_row::Store.save",
  "spans": [
    {
      "uri": "file://$DIR/V3010_invalid_operation_row.sakura",
      "content_hash": "sha256:57175066baa343e9c90ba3522cbcca1eb9714fb6cb102fe0f1e930bd25c7f191",
      "start_byte": 82,
      "end_byte": 91,
      "role": "primary"
    }
  ],
  "related_ids": [],
  "expected": null,
  "actual": null,
  "obligation": null,
  "counterexample": null,
  "explanation_uri": "sakura://explain/V3010",
  "fixes": []
}
```

## Fixed program [#fixed-program]

[`compiler/tests/ui/V3010_invalid_operation_row.fixed.sakura`](https://github.com/icantcodefyi/sakuralang/blob/master/compiler/tests/ui/V3010_invalid_operation_row.fixed.sakura), which `sakura check` accepts with no diagnostics:

```sakura
error Full

effect Store {
  fn save(key: String) -> Unit ! {Fail<Full>}
}
```