nongnu: Add mono

* nongnu/packages/dotnet.scm (mono): New variable.

nongnu/packages/dotnet.scm

@@ -21,14 +21,49 @@
   #:use-module (guix download)
   #:use-module ((guix licenses) #:prefix license:)
   #:use-module (guix packages)
+  #:use-module (guix build-system gnu)
+  #:use-module (nonguix licenses)
   #:use-module (nonguix build-system binary)
   #:use-module (gnu packages base)
   #:use-module (gnu packages compression)
+  #:use-module (gnu packages cmake)
   #:use-module (gnu packages gcc)
+  #:use-module (gnu packages python)
+  #:use-module (gnu packages perl)
   #:use-module (gnu packages icu4c)
   #:use-module (gnu packages kerberos)
   #:use-module (gnu packages instrumentation)
-  #:use-module (gnu packages tls))
+  #:use-module (gnu packages tls)
+  #:use-module (gnu packages version-control))
+
+(define-public mono
+  (package
+    (name "mono")
+    (version "6.12.0.182")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "https://download.mono-project.com/sources/mono/mono-" version ".tar.xz"))
+              (sha256 (base32 "094lzm78m33f03y7kil7vc0a3cqm2q1li1fl27qyrdgknim6ldjp"))))
+    (build-system gnu-build-system)
+    (inputs (list python
+                  cmake
+                  gcc
+                  git
+                  which
+                  perl
+                  zlib))
+    (arguments
+     `(#:parallel-build? #t
+       ;; A test, delegate2.exe, fails with an System.NotImplementedException: The method or operation is not implemented.
+       ;; Ref https://github.com/mono/mono/issues/21549
+       #:tests? #f))
+    (synopsis "Cross platform, open source .NET framework")
+    (description "Mono is a software platform designed to allow developers to
+easily create cross platform applications. It is an open source implementation
+of Microsoft's .NET Framework based on the ECMA standards for C# and the
+Common Language Runtime.")
+    (license (nonfree "MIT, BSD, MPL, Apache. See https://raw.githubusercontent.com/mono/mono/main/LICENSE and https://raw.githubusercontent.com/mono/mono/main/PATENTS.TXT"))
+    (home-page "https://www.mono-project.com/")))
 
 (define-public omnisharp
   (package