From 7a72b3ecb54c69e94e84d45c8e70eb13d26ad46e Mon Sep 17 00:00:00 2001
From: Lin Jian <me@linj.tech>
Date: Wed, 6 May 2026 01:41:56 +0800
Subject: [PATCH] writeHaskell: allow providing function for libraries

This is much safer at avoiding version mismatches.
---
 pkgs/build-support/writers/scripts.nix | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pkgs/build-support/writers/scripts.nix b/pkgs/build-support/writers/scripts.nix
index 43880c62ccaf..bb649db24575 100644
--- a/pkgs/build-support/writers/scripts.nix
+++ b/pkgs/build-support/writers/scripts.nix
@@ -17,6 +17,7 @@ let
     last
     optionalString
     strings
+    toFunction
     types
     ;
 in
@@ -751,7 +752,7 @@ rec {
     ## `pkgs.writers.writeHaskell` usage example
 
     ```nix
-    writeHaskell "missiles" { libraries = [ pkgs.haskellPackages.acme-missiles ]; } ''
+    writeHaskell "missiles" { libraries = hpkgs: [ hpkgs.acme-missiles ]; } ''
       import Acme.Missiles
 
       main = launchMissiles
@@ -777,7 +778,7 @@ rec {
     makeBinWriter {
       compileScript = ''
         cp $contentPath tmp.hs
-        ${(ghc.withPackages (_: libraries))}/bin/ghc ${lib.escapeShellArgs ghcArgs'} tmp.hs
+        ${(ghc.withPackages (toFunction libraries))}/bin/ghc ${lib.escapeShellArgs ghcArgs'} tmp.hs
         mv tmp $out
       '';
       inherit makeWrapperArgs strip;