Database.Esqueleto conundrum regarding ==. val True

While debugging a query that unexpectedly returned an empty list, I realized I had written something silly:

fetchDim cId = runDb . select . from $ \dim -> do
  where_ dim ^. DimensionIsRowKey ==. val True
  return dim

      

        
        
        
      

    

... because you can add == True

to any boolean value. Replacing it with the next unexpectedly solved problem of mine and the result was no longer empty.

fetchDim cId = runDb . select . from $ \dim -> do
  where_ dim ^. DimensionIsRowKey
  return dim

      

        
        
        
      

    

Can anyone please tell me the actual difference between the two? Why should they be?

EDIT: The backend of the database is sqlite.