From ea0d4901ab67c636e5854b1e4c8fdc34dd1abe05 Mon Sep 17 00:00:00 2001
From: Simon Michael <simon@joyful.com>
Date: Wed, 25 Nov 2020 21:01:05 -0800
Subject: [PATCH] lib: journalApplyAliases performance tweak

---
 hledger-lib/Hledger/Data/Journal.hs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hledger-lib/Hledger/Data/Journal.hs b/hledger-lib/Hledger/Data/Journal.hs
index a82a220c7..a3672ec8f 100644
--- a/hledger-lib/Hledger/Data/Journal.hs
+++ b/hledger-lib/Hledger/Data/Journal.hs
@@ -1230,6 +1230,8 @@ postingFindTag tagname p = find ((tagname==) . fst) $ postingAllTags p
 -- | Apply some account aliases to all posting account names in the journal, as described by accountNameApplyAliases.
 -- This can fail due to a bad replacement pattern in a regular expression alias.
 journalApplyAliases :: [AccountAlias] -> Journal -> Either RegexError Journal
+-- short circuit the common case, just in case there's a performance impact from txnTieKnot etc.
+journalApplyAliases [] j = Right j
 journalApplyAliases aliases j = 
   case mapM (transactionApplyAliases aliases) $ jtxns j of
     Right ts -> Right j{jtxns = ts}