gnu: Add cl-misc-extensions.

* gnu/packages/lisp-xyz.scm (sbcl-misc-extensions, cl-misc-extensions,
  ecl-misc-extensions): New variables.

gnu/packages/lisp-xyz.scm

@@ -9200,3 +9200,39 @@ archives such as those generated by the tar and cpio programs on Unix.")
 
 (define-public ecl-archive
   (sbcl-package->ecl-package sbcl-archive))
+
+(define-public sbcl-misc-extensions
+  (let ((commit "101c05112bf2f1e1bbf527396822d2f50ca6327a")
+        (revision "1"))
+    (package
+      (name "sbcl-misc-extensions")
+      (version (git-version "3.3" revision commit))
+      (source
+       (origin
+         (method git-fetch)
+         (uri (git-reference
+               (url "https://gitlab.common-lisp.net/misc-extensions/devel.git")
+               (commit commit)))
+         (file-name (git-file-name name version))
+         (sha256
+          (base32
+           "0gz5f4p70qzilnxsnf5lih2n9m4wjcw8hlw4w8mpn9jyhyppyyv0"))))
+      (build-system asdf-build-system/sbcl)
+      (synopsis "Collection of small macros and extensions for Common Lisp")
+      (description
+       "This project is intended as a catchall for small, general-purpose
+extensions to Common Lisp.  It contains:
+
+@itemize
+@item @code{new-let}, a macro that combines and generalizes @code{let},
+@code{let*} and @code{multiple-value-bind},
+@item @code{gmap}, an iteration macro that generalizes @code{map}.
+@end itemize\n")
+      (home-page "https://common-lisp.net/project/misc-extensions/")
+      (license license:public-domain))))
+
+(define-public cl-misc-extensions
+  (sbcl-package->cl-source-package sbcl-misc-extensions))
+
+(define-public ecl-misc-extensions
+  (sbcl-package->ecl-package sbcl-misc-extensions))