From 471317f4fe0a6aa6f16a27cd8a77d5cc5c6ee1f0 Mon Sep 17 00:00:00 2001
From: Albert Krewinkel <albert@zeitkraut.de>
Date: Wed, 12 Oct 2022 15:38:11 +0200
Subject: Extensions: add new function `disableExtensions`.

The function removes all elements in a second set from a base set.
Extensions in the second set that are not in the base set are ignored.
---
 src/Text/Pandoc/Extensions.hs | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'src')

diff --git a/src/Text/Pandoc/Extensions.hs b/src/Text/Pandoc/Extensions.hs
index efe4ed879..eedb823ae 100644
--- a/src/Text/Pandoc/Extensions.hs
+++ b/src/Text/Pandoc/Extensions.hs
@@ -23,6 +23,7 @@ module Text.Pandoc.Extensions ( Extension(..)
                               , extensionEnabled
                               , enableExtension
                               , disableExtension
+                              , disableExtensions
                               , getDefaultExtensions
                               , getAllExtensions
                               , pandocExtensions
@@ -193,6 +194,14 @@ enableExtension x (Extensions exts) = Extensions (Set.insert x exts)
 disableExtension :: Extension -> Extensions -> Extensions
 disableExtension x (Extensions exts) = Extensions (Set.delete x exts)
 
+-- | Removes the extensions in the second set from those in the first.
+disableExtensions :: Extensions  -- ^ base set
+                  -> Extensions  -- ^ extensions to remove
+                  -> Extensions
+disableExtensions (Extensions base) (Extensions remove) = Extensions $
+  -- keep only those extensions that are in `base` but not in `remove`.
+  base `Set.difference` remove
+
 -- | Extensions to be used with pandoc-flavored markdown.
 pandocExtensions :: Extensions
 pandocExtensions = extensionsFromList
-- 
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