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ihaskell 的求值计数不显示问题

ihaskell:

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�������8�������=���������������n������p�������������iopub{"msg_id":"a55da817-694b-4209-b3fb-3fa5d1d4b20f","msg_type":"status","session":"00b6a660-d718-4d44-ac5a-022d76b6af76","username":"","version":"5.0"}{"msg_id":"acccada4-25ca-47a7-a564-31d41db92889","msg_type":"execute_request","session":"00b6a660-d718-4d44-ac5a-022d76b6af76","username":"","version":"5.0"}{}{"execution_state":"busy"}

�������8�������=���������������u������w�������������iopub{"msg_id":"bf3d2e92-753e-4355-b1e2-4a7e7b4d8a91","msg_type":"execute_input","session":"00b6a660-d718-4d44-ac5a-022d76b6af76","username":"","version":"5.0"}{"msg_id":"acccada4-25ca-47a7-a564-31d41db92889","msg_type":"execute_request","session":"00b6a660-d718-4d44-ac5a-022d76b6af76","username":"","version":"5.0"}{}{"execution_count":1,"code":"1 + 1"}

�������8�������=���������������t������v�������������iopub{"msg_id":"22f5bc9d-5665-4e73-b781-455a8c3d8538","msg_type":"display_data","session":"00b6a660-d718-4d44-ac5a-022d76b6af76","username":"","version":"5.0"}{"msg_id":"acccada4-25ca-47a7-a564-31d41db92889","msg_type":"execute_request","session":"00b6a660-d718-4d44-ac5a-022d76b6af76","username":"","version":"5.0"}{}{"metadata":{},"data":{"text/plain":"2"}}

�������8�������=���������������n������p�������������iopub{"msg_id":"3ce4e788-41c3-478b-ad29-dee1beb3e777","msg_type":"status","session":"00b6a660-d718-4d44-ac5a-022d76b6af76","username":"","version":"5.0"}{"msg_id":"acccada4-25ca-47a7-a564-31d41db92889","msg_type":"execute_request","session":"00b6a660-d718-4d44-ac5a-022d76b6af76","username":"","version":"5.0"}{}{"execution_state":"idle"}

Python:

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�������8�������=����������������������������������iopub{"msg_id": "8218c830-a736e5ef247730fd4c0f4b41_665704_111", "msg_type": "status", "username": "ayanamists", "session": "8218c830-a736e5ef247730fd4c0f4b41", "date": "2025-04-29T06:46:43.583473Z", "version": "5.3"}{"date": "2025-04-29T06:46:43.582000Z", "msg_id": "cbe66321-a40d-4a5b-b2f8-a3a4e2c41dbe", "msg_type": "execute_request", "session": "02991bb7-a5cd-446c-b325-4880bbd5f229", "username": "", "version": "5.2"}{}{"execution_state": "busy"}

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������iopub{"msg_id": "8218c830-a736e5ef247730fd4c0f4b41_665704_112", "msg_type": "execute_input", "username": "ayanamists", "session": "8218c830-a736e5ef247730fd4c0f4b41", "date": "2025-04-29T06:46:43.583721Z", "version": "5.3"}{"date": "2025-04-29T06:46:43.582000Z", "msg_id": "cbe66321-a40d-4a5b-b2f8-a3a4e2c41dbe", "msg_type": "execute_request", "session": "02991bb7-a5cd-446c-b325-4880bbd5f229", "username": "", "version": "5.2"}{}{"code": "2 + 3", "execution_count": 4}

�������8�������=���������������������������*������iopub{"msg_id": "8218c830-a736e5ef247730fd4c0f4b41_665704_113", "msg_type": "execute_result", "username": "ayanamists", "session": "8218c830-a736e5ef247730fd4c0f4b41", "date": "2025-04-29T06:46:43.584374Z", "version": "5.3"}{"date": "2025-04-29T06:46:43.582000Z", "msg_id": "cbe66321-a40d-4a5b-b2f8-a3a4e2c41dbe", "msg_type": "execute_request", "session": "02991bb7-a5cd-446c-b325-4880bbd5f229", "username": "", "version": "5.2"}{}{"data": {"text/plain": "5"}, "metadata": {}, "execution_count": 4}

�������8�������=��������������������j�������������shell{"msg_id": "8218c830-a736e5ef247730fd4c0f4b41_665704_114", "msg_type": "execute_reply", "username": "ayanamists", "session": "8218c830-a736e5ef247730fd4c0f4b41", "date": "2025-04-29T06:46:43.587893Z", "version": "5.3"}{"date": "2025-04-29T06:46:43.582000Z", "msg_id": "cbe66321-a40d-4a5b-b2f8-a3a4e2c41dbe", "msg_type": "execute_request", "session": "02991bb7-a5cd-446c-b325-4880bbd5f229", "username": "", "version": "5.2"}{"started": "2025-04-29T06:46:43.583706Z", "dependencies_met": true, "engine": "b4934063-66a1-476b-8ccb-108e9bdcb03c", "status": "ok"}{"status": "ok", "execution_count": 4, "user_expressions": {}, "payload": []}

�������8�������=����������������������������������iopub{"msg_id": "8218c830-a736e5ef247730fd4c0f4b41_665704_115", "msg_type": "status", "username": "ayanamists", "session": "8218c830-a736e5ef247730fd4c0f4b41", "date": "2025-04-29T06:46:43.588689Z", "version": "5.3"}{"date": "2025-04-29T06:46:43.582000Z", "msg_id": "cbe66321-a40d-4a5b-b2f8-a3a4e2c41dbe", "msg_type": "execute_request", "session": "02991bb7-a5cd-446c-b325-4880bbd5f229", "username": "", "version": "5.2"}{}{"execution_state": "idle"}

分析一下这个交互，特别是与标准的 python 交互对比一下。现在的问题是，ihaskell 的求值计数不在浏览器显示。

Okay, let's break down the differences:

  1. Output Message Type:
    • IHaskell: Uses display_data (on iopub) to send the result ("2"). This message type is generic and doesn't inherently carry an execution_count.
    • Python: Uses execute_result (on iopub) to send the result ("5"). This message type specifically represents the result of an execution and includes the execution_count (here, 4).
  2. Shell Reply:
    • IHaskell: The log shown doesn't include the final execute_reply on the shell channel (though one is likely sent).
    • Python: Includes an explicit execute_reply on the shell channel, confirming success and also containing the execution_count.

Analysis for Missing Count:

The Jupyter frontend typically displays the Out[N]: prompt based on the execution_count field present in the execute_result message received on the iopub channel. Since IHaskell sends the output via display_data, which lacks this field, the frontend doesn't associate an execution count with that specific output display.

While IHaskell does correctly send the execution_count in the execute_input message (allowing the In[N]: prompt), it's not sending it with the result message in the way the standard frontend expects.

这是 ihaskell 的实现错误，还是 jupyter 前端的问题？

这更像是 IHaskell 的实现问题。

理由：

  1. Jupyter 协议规范: Jupyter 协议明确定义了 execute_result 消息类型用于传递代码单元的主要执行结果，并且这个消息类型包含 execution_count 字段。
  2. 前端行为: 前端（如 Jupyter Notebook/Lab）是按照协议规范设计的，它期望从 execute_result 消息中获取 execution_count 来显示 Out[N]:。
  3. IHaskell 的行为: IHaskell 使用了 display_data 而不是 execute_result 来发送主要结果。虽然 display_data 可以用来显示任意数据，但它不是协议中用于传递 带计数的主要执行结果 的标准方式。

因此，IHaskell 没有遵循协议推荐的最佳实践来发送最终结果，导致前端无法按预期显示计数。

按照 ihaskell 开发者的说法，单纯把消息类型进行更改是没有用的。我更怀疑是 execute_reply 造成的问题，你觉得呢？这个消息在规范里怎么说？

Okay, let's consider the execute_reply message.

Jupyter Protocol Specification for execute_reply:

  • Channel: Sent on the shell channel.
  • Purpose: Sent by the kernel when it has finished processing an execute_request. It signals the completion of the execution.
  • Content: Crucially, it contains:
    • status: indicates if the execution was successful (ok), failed (error), or aborted (abort).
    • execution_count: The same execution counter (N for In[N]) associated with the request.
    • payload: Optional list for frontend actions like paging.
    • user_expressions: Results of any user expressions requested.

Analysis:

  1. Python Example: The Python log does show a final execute_reply message on the shell channel. This message includes "status": "ok" and "execution_count": 4.
  2. IHaskell Example: The provided IHaskell log excerpt does not show the execute_reply message. It ends with an iopub status message changing to "idle". While an execute_reply should have been sent on the shell channel, it's missing from this specific log output.
  3. Potential Impact: The execute_reply message confirms the completion of the request associated with a specific execution_count. The frontend uses this, along with messages on iopub like execute_result, to manage the state of the cell (e.g., removing the busy indicator, potentially finalizing the display).

Conclusion:

You have a valid point. While execute_result is the standard way to associate the output value with the execution_count for the Out[N]: prompt, the execute_reply confirms the overall completion of the request for that count.

  • If IHaskell is not sending a correct execute_reply (or if it's somehow malformed), the frontend might not properly register the completion of the execution cycle for that execution_count, which could interfere with displaying the Out[N]: properly, even if the result data arrived via display_data.
  • The IHaskell developers might be correct that simply changing display_data to execute_result isn't enough if the corresponding execute_reply is also missing or incorrect. Both are essential parts of the execution lifecycle according to the protocol.

It seems both the use of display_data instead of execute_result and potential issues with the execute_reply could be contributing factors. The absence of execute_reply in the provided IHaskell log is suspicious.