Compatibility with GHC 8.10 and template-haskell 2.16.

Taken from 
https://raw.githubusercontent.com/archlinux/svntogit-community/packages/haskell-language-haskell-extract/trunk/ghc-8.10.patch

diff --git a/src/Language/Haskell/Extract.hs b/src/Language/Haskell/Extract.hs
index 3e8958b..43dfe04 100644
--- a/src/Language/Haskell/Extract.hs
+++ b/src/Language/Haskell/Extract.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 module Language.Haskell.Extract (
   functionExtractor,
   functionExtractorMap,
@@ -25,7 +26,11 @@ extractAllFunctions pattern =
 functionExtractor :: String -> ExpQ
 functionExtractor pattern =
   do functions <- extractAllFunctions pattern
-     let makePair n = TupE [ LitE $ StringL n , VarE $ mkName n]
+     let makePair n = TupE
+#if MIN_VERSION_template_haskell(2,16,0)
+                           $ map Just
+#endif
+                           [ LitE $ StringL n , VarE $ mkName n]
      return $ ListE $ map makePair functions
 
 
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<div class='path'>path: <a href='/guix/log/?id=a437bd9180d1af0f84229d4ae3e9cd0ab93d9fa0&amp;showmsg=1'>root</a>/<a href='/guix/log/gnu?id=a437bd9180d1af0f84229d4ae3e9cd0ab93d9fa0&amp;showmsg=1'>gnu</a>/<a href='/guix/log/gnu/packages?id=a437bd9180d1af0f84229d4ae3e9cd0ab93d9fa0&amp;showmsg=1'>packages</a>/<a href='/guix/log/gnu/packages/patches?id=a437bd9180d1af0f84229d4ae3e9cd0ab93d9fa0&amp;showmsg=1'>patches</a>/<a href='/guix/log/gnu/packages/patches/remake-impure-dirs.patch?id=a437bd9180d1af0f84229d4ae3e9cd0ab93d9fa0&amp;showmsg=1'>remake-impure-dirs.patch</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/patches/remake-impure-dirs.patch?id=a437bd9180d1af0f84229d4ae3e9cd0ab93d9fa0'>Collapse</a>)</th><th class='left'>Author</th></tr>
<tr class='logheader'><td><span title='2020-08-01 14:00:47 -0500'>2020-08-01</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/patches/remake-impure-dirs.patch?id=86f86cffd822afc012e308490e9931a66ce924aa'>gnu: Add Remake.</a></td><td>Eric Bavier</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/debug.scm (remake): New variable.
* gnu/packages/patches/remake-impure-dirs.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.


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