Invalid token: = 

Hi,

I updated my haskell-mode with MELPA and I keep having 

```
Invalid token: = 
```

here a snippet

```
loadPhases :: M.Map String (Phase g l) -> [String] -> Maybe [Phase g l]
loadPhases ps = traverse go
```

The syntax looks good to me. That prevents me from editing my buffer. Is it possible to disable such behavior ?  

Thanks for your time.
