extra: hledger-rewrite script

extra/hledger-rewrite.hs

@@ -0,0 +1,30 @@
+#!/usr/bin/env runhaskell
+{-|
+hledger-rewrite PATTERNS --add-posting "ACCT  AMTEXPR" ...
+
+Skeleton for a minimal generic rewriter of journal entries.
+Reads the default journal and prints the entries, like print,
+but adds the specified postings to any entries matching PATTERNS.
+
+|-}
+
+import Hledger.Data.Types (Journal(..))
+import Hledger
+import Hledger.Cli
+
+main = do
+  putStrLn "(-f option not supported)"
+  opts <- getCliOpts (defCommandMode ["hledger-rewrite"])
+  withJournalDo opts $
+    \opts j@Journal{jtxns=ts} -> print' opts j{jtxns=map rewrite ts}
+    where 
+      rewrite t = if matched t then t{tpostings=tpostings t ++ newps t}
+                               else t
+      matched t = Acct "^income" `matchesTransaction` t
+      newps t = [generatePosting t "(Reserve)" (`divideMixedAmount` 10)]
+      generatePosting t acct amtfn = nullposting{paccount = accountNameWithoutPostingType acct
+                                                ,ptype    = accountNamePostingType acct
+                                                ,pamount  = amtfn amt
+                                                }
+        where
+          amt = pamount $ head $ filter (Acct "^income" `matchesPosting`) $ tpostings t

hledger-lib/Hledger/Read.hs

@@ -18,6 +18,7 @@ module Hledger.Read (
        requireJournalFileExists,
        ensureJournalFileExists,
        -- * Parsers used elsewhere
+       postingp,
        accountname,
        amountp,
        amountp',

hledger-lib/Hledger/Read/JournalReader.hs

@@ -29,6 +29,7 @@ module Hledger.Read.JournalReader (
   datetime,
   code,
   accountname,
+  postingp,
   amountp,
   amountp',
   mamountp',