Explicit export lists for Main (#9890)

* Explicit export lists for Main Lack of explicit export list can degrade performance. The Main module in particular should always have an explicit export list that contains just the main function. * add changelog --------- Co-authored-by: Artem Pelenitsyn <[email protected]> Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
haskell · Dec 2, 2024 · 55ccc0a · 55ccc0a
1 parent da40ea6
commit 55ccc0a
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diff --git a/cabal-install/src/Distribution/Client/Init/Defaults.hs b/cabal-install/src/Distribution/Client/Init/Defaults.hs
@@ -165,15 +165,15 @@ myLibHs =
 
 myExeHs :: [String]
 myExeHs =
-  [ "module Main where"
+  [ "module Main (main) where"
   , ""
   , "main :: IO ()"
   , "main = putStrLn \"Hello, Haskell!\""
   ]
 
 myLibExeHs :: [String]
 myLibExeHs =
-  [ "module Main where"
+  [ "module Main (main) where"
   , ""
   , "import qualified MyLib (someFunc)"
   , ""

diff --git a/changelog.d/pr-9890 b/changelog.d/pr-9890
@@ -0,0 +1,10 @@
+synopsis: `cabal init` generates explicit export lists for Main
+packages: cabal-install
+prs: #9890
+issues: #9889
+
+description: {
+
+- Lack of explicit export list can degrade performance. The `Main` module in particular should always have an explicit export list that contains just the main function. Then, the compiler can do more aggressive optimizations on all the other non-exported functions.
+
+}