Haskell HasCallStack 意外行为

Question

以下是我们拥有的一个非常常见的模式的简化，其中您有一些重试组合器包装 IO 操作。我想要一些堆栈跟踪，所以我添加了HasCallStack约束，但结果堆栈跟踪并不令人满意：

import Control.Monad (forM_)
import GHC.Stack

httpCall :: HasCallStack => IO ()
httpCall = do
  putStrLn $ prettyCallStack callStack
  print "http resolved"

retry :: HasCallStack => IO () -> IO ()
retry op =
  forM_ [1] $ \i ->
    op

main :: IO ()
main = retry httpCall

堆栈跟踪：

CallStack (from HasCallStack):
  httpCall, called at main.hs:16:14 in main:Main
"http resolved"

我假设HasCallStack约束得到解析main以适应参数类型，retry所以我将约束添加到参数类型：

CallStack (from HasCallStack):
  httpCall, called at main.hs:16:14 in main:Main
"http resolved"

现在堆栈跟踪还有 2 个条目，它们都非常令人惊讶：

CallStack (from HasCallStack):
  httpCall, called at main.hs:17:14 in main:Main
  op, called at main.hs:14:5 in main:Main
  retry, called at main.hs:17:8 in main:Main
"http resolved"

问题

1. httpCall报告它是从main（第 17 行）调用的
2. op 报告正确的行，但在开始的堆栈跟踪中看到它是非常意外的。

我预计会出现以下情况：

CallStack (from HasCallStack):
  httpCall, called at main.hs:14:5 in main:Main
  retry, called at main.hs:17:8 in main:Main
"http resolved"