From 17501d776b9af5a30f4dba37fb9c34a60a44bebb Mon Sep 17 00:00:00 2001
From: Tsung-Ju Chiang <71379180+tsung-ju@users.noreply.github.com>
Date: Wed, 28 May 2025 15:15:28 +0800
Subject: [PATCH] agda.withPackages: allow installing Agda without GHC using
 `ghc = null;`

---
 doc/languages-frameworks/agda.section.md | 2 ++
 pkgs/build-support/agda/default.nix      | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/doc/languages-frameworks/agda.section.md b/doc/languages-frameworks/agda.section.md
index 6b9e577f8119..d5a1c6ef08a3 100644
--- a/doc/languages-frameworks/agda.section.md
+++ b/doc/languages-frameworks/agda.section.md
@@ -121,6 +121,8 @@ agda.withPackages {
 }
 ```
 
+To install Agda without GHC, use `ghc = null;`.
+
 ## Writing Agda packages {#writing-agda-packages}
 
 To write a nix derivation for an Agda library, first check that the library has a `*.agda-lib` file.
diff --git a/pkgs/build-support/agda/default.nix b/pkgs/build-support/agda/default.nix
index 957b423c31f6..45fa66ad4587 100644
--- a/pkgs/build-support/agda/default.nix
+++ b/pkgs/build-support/agda/default.nix
@@ -66,7 +66,7 @@ let
       ''
         mkdir -p $out/bin
         makeWrapper ${Agda.bin}/bin/agda $out/bin/agda \
-          --add-flags "--with-compiler=${ghc}/bin/ghc" \
+          ${lib.optionalString (ghc != null) ''--add-flags "--with-compiler=${ghc}/bin/ghc"''} \
           --add-flags "--library-file=${library-file}"
         ln -s ${Agda.bin}/bin/agda-mode $out/bin/agda-mode
       '';