From 01e0c34b850855f35555dda1873ba149a05f76ea Mon Sep 17 00:00:00 2001
From: Simon Michael <simon@joyful.com>
Date: Thu, 17 Jul 2025 07:51:05 -0700
Subject: [PATCH] dev: Hledger.Utils.IO: getFlag helper, like getOpt

---
 hledger-lib/Hledger/Utils/IO.hs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/hledger-lib/Hledger/Utils/IO.hs b/hledger-lib/Hledger/Utils/IO.hs
index 0ad91e577..fea742dce 100644
--- a/hledger-lib/Hledger/Utils/IO.hs
+++ b/hledger-lib/Hledger/Utils/IO.hs
@@ -52,6 +52,7 @@ module Hledger.Utils.IO (
 
   -- * Command line parsing
   progArgs,
+  getFlag,
   getOpt,
   parseYN,
   parseYNA,
@@ -500,6 +501,15 @@ progArgs = unsafePerformIO getArgs
 --  a few cases involving --color (see useColorOnStdoutUnsafe)
 --  --debug
 
+-- | Given one or more long or short flag names,
+-- report whether this flag is present in the command line.
+-- Concatenated short flags (-a -b written as -ab) are not supported.
+getFlag :: [String] -> IO Bool
+getFlag names = do
+  let flags = map toFlag names
+  args <- getArgs
+  return $ any (`elem` args) flags
+
 -- | Given one or more long or short option names, read the rightmost value of this option from the command line arguments.
 -- If the value is missing raise an error.
 -- Concatenated short flags (-a -b written as -ab) are not supported.