An idempotence issue involving ($) and multi-way if

[mrkkrp]

Here is an example from hledger (which should be enabled on CI when we fix this):

accts = dbg5 "accts to show" $ -- no need to nub/sort, accountTree will
  if | declared     && not used -> matcheddeclaredaccts
     | not declared && used     -> matchedusedaccts
     | otherwise                -> matcheddeclaredaccts ++ matchedusedaccts

On the first pass we get:

accts =
  dbg5 "accts to show"
    $ if -- no need to nub/sort, accountTree will
      | declared && not used -> matcheddeclaredaccts
      | not declared && used -> matchedusedaccts
      | otherwise -> matcheddeclaredaccts ++ matchedusedaccts

On the second pass:

accts =
  dbg5 "accts to show"
    $ if
      -- no need to nub/sort, accountTree will
      | declared && not used -> matcheddeclaredaccts
      | not declared && used -> matchedusedaccts
      | otherwise -> matcheddeclaredaccts ++ matchedusedaccts

[utdemir]

I think this has the same underlying issue with #340.

[mrkkrp]

Tested with current master; this is no longer an issue.