import: utils: 'recursive-import' returns packages in topological order.

* guix/import/utils.scm (topological-sort): New procedure.
(recursive-import): Rewrite to use it.
* tests/import-utils.scm ("recursive-import"): New test.
* guix/import/cran.scm (cran->guix-package): Always return two values.
* guix/scripts/import/cran.scm (guix-import-cran): Remove 'reverse' call
on 'cran-recursive-import' result.
* guix/scripts/import/crate.scm (guix-import-crate): Likewise.
* guix/scripts/import/elpa.scm (guix-import-elpa): Likewise.
* guix/scripts/import/gem.scm (guix-import-gem): Likewise.
* guix/scripts/import/hackage.scm (guix-import-hackage): Likewise.
* guix/scripts/import/opam.scm (guix-import-opam): Likewise.
* guix/scripts/import/pypi.scm (guix-import-pypi): Likewise.
* guix/scripts/import/stackage.scm (guix-import-stackage): Likewise.
* tests/gem.scm ("gem-recursive-import"): Change the order of package
expressions accordingly.

8 files changed, 18 insertions, 26 deletions

diff --git a/guix/scripts/import/cran.scm b/guix/scripts/import/cran.scm
index b6592f78a9..d47be584ae 100644
--- a/guix/scripts/import/cran.scm
+++ b/guix/scripts/import/cran.scm
@@ -98,10 +98,9 @@ Import and convert the CRAN package for PACKAGE-NAME.\n"))
        (if (assoc-ref opts 'recursive)
            ;; Recursive import
            (map package->definition
-                (reverse
-                 (stream->list
-                  (cran-recursive-import package-name
-                                         (or (assoc-ref opts 'repo) 'cran)))))
+                (stream->list
+                 (cran-recursive-import package-name
+                                        (or (assoc-ref opts 'repo) 'cran))))
            ;; Single import
            (let ((sexp (cran->guix-package package-name
                                            (or (assoc-ref opts 'repo) 'cran))))
diff --git a/guix/scripts/import/crate.scm b/guix/scripts/import/crate.scm
index 4690cceb4d..a388dc368d 100644
--- a/guix/scripts/import/crate.scm
+++ b/guix/scripts/import/crate.scm
@@ -101,9 +101,8 @@ Import and convert the crate.io package for PACKAGE-NAME.\n"))
                    `(define-public ,(string->symbol name)
                       ,pkg))
                   (_ #f))
-                (reverse
-                 (stream->list
-                  (crate-recursive-import name))))
+                (stream->list
+                 (crate-recursive-import name)))
            (let ((sexp (crate->guix-package name version)))
              (unless sexp
                (leave (G_ "failed to download meta-data for package '~a'~%")
diff --git a/guix/scripts/import/elpa.scm b/guix/scripts/import/elpa.scm
index f1ed5016ba..3cdb49eae4 100644
--- a/guix/scripts/import/elpa.scm
+++ b/guix/scripts/import/elpa.scm
@@ -101,10 +101,9 @@ Import the latest package named PACKAGE-NAME from an ELPA repository.\n"))
                    `(define-public ,(string->symbol name)
                       ,pkg))
                   (_ #f))
-                (reverse
-                 (stream->list
-                  (elpa-recursive-import package-name
-                                         (or (assoc-ref opts 'repo) 'gnu)))))
+                (stream->list
+                 (elpa-recursive-import package-name
+                                        (or (assoc-ref opts 'repo) 'gnu))))
            (let ((sexp (elpa->guix-package package-name (assoc-ref opts 'repo))))
              (unless sexp
                (leave (G_ "failed to download package '~a'~%") package-name))
diff --git a/guix/scripts/import/gem.scm b/guix/scripts/import/gem.scm
index b6d9ccaae4..afd7bf6d3e 100644
--- a/guix/scripts/import/gem.scm
+++ b/guix/scripts/import/gem.scm
@@ -95,9 +95,8 @@ Import and convert the RubyGems package for PACKAGE-NAME.\n"))
                    `(define-public ,(string->symbol name)
                       ,pkg))
                   (_ #f))
-                (reverse
-                 (stream->list
-                  (gem-recursive-import package-name 'rubygems))))
+                (stream->list
+                 (gem-recursive-import package-name 'rubygems)))
            (let ((sexp (gem->guix-package package-name)))
              (unless sexp
                (leave (G_ "failed to download meta-data for package '~a'~%")
diff --git a/guix/scripts/import/hackage.scm b/guix/scripts/import/hackage.scm
index f4aac61078..023cc1e700 100644
--- a/guix/scripts/import/hackage.scm
+++ b/guix/scripts/import/hackage.scm
@@ -130,9 +130,8 @@ version.\n"))
                              `(define-public ,(string->symbol name)
                                 ,pkg))
                             (_ #f))
-                          (reverse
-                           (stream->list
-                            (apply hackage-recursive-import arguments))))
+                          (stream->list
+                           (apply hackage-recursive-import arguments)))
                      ;; Single import
                      (apply hackage->guix-package arguments))))
       (unless sexp (error-fn))
diff --git a/guix/scripts/import/opam.scm b/guix/scripts/import/opam.scm
index 2d249a213f..10410f714d 100644
--- a/guix/scripts/import/opam.scm
+++ b/guix/scripts/import/opam.scm
@@ -94,9 +94,8 @@ Import and convert the opam package for PACKAGE-NAME.\n"))
                    `(define-public ,(string->symbol name)
                       ,pkg))
                   (_ #f))
-                (reverse
-                 (stream->list
-                  (opam-recursive-import package-name))))
+                (stream->list
+                 (opam-recursive-import package-name)))
            ;; Single import
            (let ((sexp (opam->guix-package package-name)))
              (unless sexp
diff --git a/guix/scripts/import/pypi.scm b/guix/scripts/import/pypi.scm
index 7bd83818ba..f5f34b3c1b 100644
--- a/guix/scripts/import/pypi.scm
+++ b/guix/scripts/import/pypi.scm
@@ -95,9 +95,8 @@ Import and convert the PyPI package for PACKAGE-NAME.\n"))
                    `(define-public ,(string->symbol name)
                       ,pkg))
                   (_ #f))
-                (reverse
-                 (stream->list
-                  (pypi-recursive-import package-name))))
+                (stream->list
+                 (pypi-recursive-import package-name)))
            ;; Single import
            (let ((sexp (pypi->guix-package package-name)))
              (unless sexp
diff --git a/guix/scripts/import/stackage.scm b/guix/scripts/import/stackage.scm
index b4b12581bf..9325341c84 100644
--- a/guix/scripts/import/stackage.scm
+++ b/guix/scripts/import/stackage.scm
@@ -110,9 +110,8 @@ Import and convert the LTS Stackage package for PACKAGE-NAME.\n"))
                              `(define-public ,(string->symbol name)
                                 ,pkg))
                             (_ #f))
-                          (reverse
-                           (stream->list
-                            (apply stackage-recursive-import arguments))))
+                          (stream->list
+                           (apply stackage-recursive-import arguments)))
                      ;; Single import
                      (apply stackage->guix-package arguments))))
       (unless sexp (error-fn))