import: cpan: Support recursive imports.

* guix/import/cpan.scm (cpan-module->sexp): Return two values.
(cpan->guix-package): Add #:version.  Return two values.
(cpan-recursive-import): New procedure.
* guix/scripts/import/cpan.scm (show-help, %options): Add ‘-r’.
(guix-import-cpan): Adjust accordingly.

Change-Id: Id167c7ddd079f4e04650ce7cc1692a9de36cd8fe
Signed-off-by: Ludovic Courtès <ludo@gnu.org>

3 files changed, 66 insertions, 30 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 454dd66c18..8297ad2ca6 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -14207,6 +14207,17 @@ The command below imports metadata for the Acme::Boolean Perl module:
 guix import cpan Acme::Boolean
 @end example
 
+Like many other importers, the @code{cpan} importer supports recursive
+imports:
+
+@table @code
+@item --recursive
+@itemx -r
+Traverse the dependency graph of the given upstream package recursively
+and generate package expressions for all those packages that are not yet
+in Guix.
+@end table
+
 @item cran
 @cindex CRAN
 @cindex Bioconductor
diff --git a/guix/import/cpan.scm b/guix/import/cpan.scm
index b87736eef6..85e5e69098 100644
--- a/guix/import/cpan.scm
+++ b/guix/import/cpan.scm
@@ -37,12 +37,14 @@
   #: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)
+                #:select (factorize-uri recursive-import))
   #: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 +286,39 @@ in RELEASE, a <cpan-release> record."
                                             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 +363,11 @@ in RELEASE, a <cpan-release> record."
         (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..4ddd85ee57 100644
--- a/guix/scripts/import/cpan.scm
+++ b/guix/scripts/import/cpan.scm
@@ -44,6 +44,8 @@ Import and convert the CPAN package for PACKAGE-NAME.\n"))
   (display (G_ "
   -h, --help             display this help and exit"))
   (display (G_ "
+  -r, --recursive        import missing packages recursively"))
+  (display (G_ "
   -V, --version          display version information and exit"))
   (newline)
   (show-bug-report-information))
@@ -54,6 +56,9 @@ Import and convert the CPAN package for PACKAGE-NAME.\n"))
                  (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 +83,20 @@ Import and convert the CPAN package for PACKAGE-NAME.\n"))
                            (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 ...)