From 70dfcec86830d56ee3e20fb34f37f760c5b222b7 Mon Sep 17 00:00:00 2001
From: Ghislain Vaillant <ghislain.vaillant@inria.fr>
Date: Sun, 16 Aug 2026 09:48:13 +0200
Subject: hep: Add thepeg.

* guix-science/packages/hep.scm (thepeg): New variable.
---
 guix-science/packages/hep.scm | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/guix-science/packages/hep.scm b/guix-science/packages/hep.scm
index b38fcf0..bf2265a 100644
--- a/guix-science/packages/hep.scm
+++ b/guix-science/packages/hep.scm
@@ -25,6 +25,7 @@
   #:use-module (gnu packages serialization)
   #:use-module (gnu packages statistics)
   #:use-module (gnu packages swig)
+  #:use-module (gnu packages time)
   #:use-module (guix build-system cmake)
   #:use-module (guix build-system gnu)
   #:use-module (guix build-system pyproject)
@@ -767,6 +768,46 @@ physics from the Standard Model to BSM theories, and from perturbative jet,
 boson and top-quarks to hadron decays, inclusive QCD, and Heavy Ion physics.")
     (license license:gpl3)))
 
+;; FIXME: Build with rivet support.
+;; FIXME: Build with zlib support.
+(define-public thepeg
+  ;; Upstream does not tag releases.
+  (let ((commit "5afed9e448f4be43c32c629e11edc011bfd12707")
+        (revision "0")
+        (version "2.3.0"))
+    (package
+      (name "thepeg")
+      (version (git-version version revision commit))
+      (source
+       (origin
+         (method git-fetch)
+         (uri (git-reference
+               (url "https://gitlab.com/hep-mirrors/thepeg.git")
+               (commit commit)))
+         (file-name (git-file-name name version))
+         (sha256
+          (base32 "1jij79ycb3x3cid06iz9x3xln8sypgdwxph5j8srrgk5x6ccdqqx"))))
+      (build-system gnu-build-system)
+      (arguments
+       (list
+        #:configure-flags
+        #~(list "--with-hepmc" "--with-hepmcversion=3" "--without-zlib")
+        #:phases
+        #~(modify-phases %standard-phases
+            (add-after 'unpack 'fix-lhapdf-flags
+              (lambda _
+                (substitute* "m4/lhapdf.m4"
+                  (("LHAPDF_LDFLAGS=.*\"")
+                   "LHAPDF_LDFLAGS=\"`${lhaconfig} --ldflags`\"")))))))
+      (inputs (list fastjet gsl hepmc3 lhapdf))
+      (native-inputs (list autoconf automake boost libtool time))
+      (home-page "https://thepeg.hepforge.org/")
+      (synopsis "Toolkit for High Energy Physics Event Generation")
+      (description
+       "ThePEG is a toolkit for implementing HEP event generators, used as the
+common event-generation framework underlying Herwig 7.")
+      (license license:gpl3))))
+
 (define-public yoda
   (package
     (name "yoda")
-- 
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