lib: memoise accountNameApplyAliases too ?

This adds a accountNameApplyAliasesMemo, which memoises the result of
applying a set of aliases (simple and regex) to an account name. In
theory this should reduce more repetitive work, but in practice it
doesn't seem to make a difference, so it's unused for now.

hledger-lib/Hledger/Data/Posting.hs

@@ -37,6 +37,7 @@ module Hledger.Data.Posting (
   joinAccountNames,
   concatAccountNames,
   accountNameApplyAliases,
+  accountNameApplyAliasesMemo,
   -- * arithmetic
   sumPostings,
   -- * rendering
@@ -231,6 +232,10 @@ accountNameApplyAliases aliases a = accountNameWithPostingType atype aname'
              aname
              aliases
 
+-- | Memoising version of accountNameApplyAliases, maybe overkill.
+accountNameApplyAliasesMemo :: [AccountAlias] -> AccountName -> AccountName
+accountNameApplyAliasesMemo aliases = memo (accountNameApplyAliases aliases)
+
 -- aliasMatches :: AccountAlias -> AccountName -> Bool
 -- aliasMatches (BasicAlias old _) a = old `isAccountNamePrefixOf` a
 -- aliasMatches (RegexAlias re  _) a = regexMatchesCI re a

hledger-lib/Hledger/Read/JournalReader.hs

@@ -664,6 +664,7 @@ modifiedaccountnamep = do
   a <- accountnamep
   return $
     accountNameApplyAliases aliases $
+     -- XXX accountNameApplyAliasesMemo ? doesn't seem to make a difference
     joinAccountNames parent
     a