From daad170113e1e2e83ccf10ba33c0d321075bbd18 Mon Sep 17 00:00:00 2001
From: Daniil Iaitskov <dyaitskov@gmail.com>
Date: Thu, 18 Sep 2025 21:04:05 +0300
Subject: [PATCH] haskellPackages.callHackageDirect: add optional candidate
 attribute

---
 pkgs/development/haskell-modules/make-package-set.nix | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/haskell-modules/make-package-set.nix b/pkgs/development/haskell-modules/make-package-set.nix
index 320b331fc25d..bdc71b928a2c 100644
--- a/pkgs/development/haskell-modules/make-package-set.nix
+++ b/pkgs/development/haskell-modules/make-package-set.nix
@@ -262,6 +262,7 @@ package-set { inherit pkgs lib callPackage; } self
       pkg,
       ver,
       sha256,
+      candidate ? false,
       rev ? {
         revision = null;
         sha256 = null;
@@ -271,7 +272,11 @@ package-set { inherit pkgs lib callPackage; } self
     let
       pkgver = "${pkg}-${ver}";
       firstRevision = self.callCabal2nix pkg (pkgs.fetchzip {
-        url = "mirror://hackage/${pkgver}/${pkgver}.tar.gz";
+        url =
+          if candidate then
+            "mirror://hackage/${pkgver}/candidate/${pkgver}.tar.gz"
+          else
+            "mirror://hackage/${pkgver}/${pkgver}.tar.gz";
         inherit sha256;
       }) args;
     in