[bug#68358] guix: import: cpan: add recursive

diff --git a/guix/import/cpan.scm b/guix/import/cpan.scm
index b87736eef6..2090da275d 100644
--- a/guix/import/cpan.scm
+++ b/guix/import/cpan.scm
@@ -37,12 +37,13 @@  (define-module (guix import cpan)
   #:use-module (guix utils)
   #:use-module (guix base32)
   #:use-module ((guix download) #:select (download-to-store url-fetch))
-  #:use-module ((guix import utils) #:select (factorize-uri))
+  #:use-module (guix import utils)
   #:use-module (guix import json)
   #:use-module (guix packages)
   #:use-module (guix upstream)
   #:use-module (guix derivations)
   #:export (cpan->guix-package
+            cpan-recursive-import
             metacpan-url->mirror-url
             %cpan-updater
 
@@ -284,35 +285,42 @@  (define (cpan-module->sexp release)
                                             upstream-input-downstream-name)
                                    inputs)))))))
 
-  (let ((tarball (with-store store
+  (let* ((tarball (with-store store
                    (download-to-store store source-url)))
-        (inputs (cpan-module-inputs release)))
-    `(package
-       (name ,(cpan-name->downstream-name name))
-       (version ,version)
-       (source (origin
-                 (method url-fetch)
-                 (uri (string-append ,@(factorize-uri source-url version)))
-                 (sha256
-                  (base32
-                   ,(bytevector->nix-base32-string (file-sha256 tarball))))))
-       (build-system perl-build-system)
-       ,@(maybe-inputs 'native-inputs
-                       (filter (upstream-input-type-predicate 'native)
-                               inputs))
-       ,@(maybe-inputs 'propagated-inputs
-                       (filter (upstream-input-type-predicate 'propagated)
-                               inputs))
-       (home-page ,(cpan-home name))
-       (synopsis ,(cpan-release-abstract release))
-       (description fill-in-yourself!)
-       (license ,(string->license (cpan-release-license release))))))
+         (inputs (cpan-module-inputs release))
+         (sexp
+           `(package
+              (name ,(cpan-name->downstream-name name))
+              (version ,version)
+              (source (origin
+                        (method url-fetch)
+                        (uri (string-append ,@(factorize-uri source-url version)))
+                        (sha256
+                          (base32
+                            ,(bytevector->nix-base32-string (file-sha256 tarball))))))
+              (build-system perl-build-system)
+              ,@(maybe-inputs 'native-inputs
+                              (filter (upstream-input-type-predicate 'native)
+                                      inputs))
+              ,@(maybe-inputs 'propagated-inputs
+                              (filter (upstream-input-type-predicate 'propagated)
+                                      inputs))
+              (home-page ,(cpan-home name))
+              (synopsis ,(cpan-release-abstract release))
+              (description fill-in-yourself!)
+              (license ,(string->license (cpan-release-license release))))))
+    (values
+      sexp
+      (map upstream-input-name inputs))
+    ))
 
-(define (cpan->guix-package module-name)
+(define* (cpan->guix-package module-name #:key version #:allow-other-keys)
   "Fetch the metadata for PACKAGE-NAME from metacpan.org, and return the
 `package' s-expression corresponding to that package, or #f on failure."
   (let ((release (cpan-fetch (module->name module-name))))
-    (and=> release cpan-module->sexp)))
+    (if release
+      (cpan-module->sexp release)
+      (values #f '()))))
 
 (define cpan-package?
   (let ((cpan-rx (make-regexp (string-append "("
@@ -357,6 +365,11 @@  (define* (latest-release package #:key (version #f))
         (urls (list url))
         (inputs (cpan-module-inputs release)))))))
 
+(define* (cpan-recursive-import package-name)
+  (recursive-import package-name
+                    #:repo->guix-package cpan->guix-package
+                    #:guix-name (compose cpan-name->downstream-name module->name)))
+
 (define %cpan-updater
   (upstream-updater
    (name 'cpan)
diff --git a/guix/scripts/import/cpan.scm b/guix/scripts/import/cpan.scm
index bdf5a1e423..cab6424068 100644
--- a/guix/scripts/import/cpan.scm
+++ b/guix/scripts/import/cpan.scm
@@ -43,6 +43,9 @@  (define (show-help)
 Import and convert the CPAN package for PACKAGE-NAME.\n"))
   (display (G_ "
   -h, --help             display this help and exit"))
+  (display (G_ "
+  -r, --recursive        generate package expressions for all Gem packages\
+ that are not yet in Guix"))
   (display (G_ "
   -V, --version          display version information and exit"))
   (newline)
@@ -54,6 +57,9 @@  (define %options
                  (lambda args
                    (show-help)
                    (exit 0)))
+         (option '(#\r "recursive") #f #f
+                 (lambda (opt name arg result)
+                   (alist-cons 'recursive #t result)))
          (option '(#\V "version") #f #f
                  (lambda args
                    (show-version-and-exit "guix import cpan")))
@@ -78,11 +84,20 @@  (define (guix-import-cpan . args)
                            (reverse opts))))
     (match args
       ((package-name)
-       (let ((sexp (cpan->guix-package package-name)))
-         (unless sexp
-           (leave (G_ "failed to download meta-data for package '~a'~%")
-                  package-name))
-         sexp))
+       (let ((sexp
+               (if (assoc-ref opts 'recursive)
+                 (map (match-lambda
+                        ((and ('package ('name name) . rest) pkg)
+                         `(define-public ,(string->symbol name)
+                                         ,pkg))
+                        (_ #f))
+                      (cpan-recursive-import package-name))
+                 (let ((sexp (cpan->guix-package package-name)))
+                   sexp))))
+             (unless sexp
+               (leave (G_ "failed to download meta-data for package '~a'~%")
+                      package-name))
+             sexp))
       (()
        (leave (G_ "too few arguments~%")))
       ((many ...)