Avoid unnecessary use of run

The top-level of a QSM test typically looks something like this:

```haskell
forAllCommands ... $ \cmds -> QC.monadicIO $ do
  (hist, prop) <- .... runCommands ...
  prettyCommands ...
```

The problem is that `runCommands` lives in `PropertyM`. This makes it
impossible to do any kind of bracketing. Fortunately, it turns out that this
use of `PropertyM` is actually not needed at all. In this commit, I add
`runCommands'`, which lives in `m`. To avoid breaking backwards compatibility,
`runCommands` still lives in `PropertyM` and is a combination of `run` and
`runCommands'`.

This will allow us to do something like:

```haskell
forAllCommands ... $ \cmds -> QC.monadicIO $ do
  (hist, prop) <- .... run (bracket ... $ \r -> runCommands' .. r .. ) ...
  prettyCommands ...
```

Co-authored-by: Thomas Winant <[email protected]>
Signed-off-by: Edsko de Vries <[email protected]>

Author: edsko

src/Test/StateMachine/Sequential.hs

@@ -35,6 +35,7 @@ module Test.StateMachine.Sequential
   , ShouldShrink(..)
   , initValidateEnv
   , runCommands
+  , runCommands'
   , getChanContents
   , Check(..)
   , executeCommands
@@ -325,9 +326,16 @@ runCommands :: (Show (cmd Concrete), Show (resp Concrete))
             => StateMachine model cmd m resp
             -> Commands cmd resp
             -> PropertyM m (History cmd resp, model Concrete, Reason)
-runCommands sm@StateMachine { initModel, cleanup } = run . go
-  where
-    go cmds = mask $ \restore -> do
+runCommands sm cmds = run $ runCommands' sm cmds
+
+runCommands' :: (Show (cmd Concrete), Show (resp Concrete))
+             => (Rank2.Traversable cmd, Rank2.Foldable resp)
+             => (MonadMask m, MonadIO m)
+             => StateMachine model cmd m resp
+             -> Commands cmd resp
+             -> m (History cmd resp, model Concrete, Reason)
+runCommands' sm@StateMachine { initModel, cleanup } cmds =
+    mask $ \restore -> do
       hchan <- restore newTChanIO
       (reason, (_, _, _, model)) <- restore
         (runStateT