derivations: 'derivation' and related procedures return a single value.

* guix/derivations.scm (derivation->output-path,
  derivation->output-paths): New procedures.
  (derivation-path->output-path): Use 'derivation->output-path'.
  (derivation-path->output-paths): Use 'derivation->output-paths'.
  (derivation): Accept 'derivation?' objects as inputs.  Return a single
  value.
  (build-derivations): New procedure.
  (compiled-modules): Use 'derivation->output-paths'.
  (build-expression->derivation)[source-path]: Add case for when the
  input matches 'derivation?'.
  [prologue]: Accept 'derivation?' objects in INPUTS.
  [mod-dir, go-dir]: Use 'derivation->output-path'.
* guix/download.scm (url-fetch): Adjust to the single-value return.
* guix/packages.scm (package-output): Use 'derivation->output-path'.
* guix/scripts/build.scm (guix-build): When the argument is
  'derivation-path?', pass it through 'read-derivation'.
  Use 'derivation-file-name' to print out the .drv file names, and to
  register them.  Use 'derivation->output-path' instead of
  'derivation-path->output-path'.
* guix/scripts/package.scm (roll-back): Adjust to the single-value
  return.
  (guix-package): Use 'derivation->output-path'.
* guix/ui.scm (show-what-to-build): Adjust to deal with 'derivation?'
  objects instead of .drv file names.
* gnu/system/grub.scm (grub-configuration-file): Use
  'derivation->output-path' instead of 'derivation-path->output-path'.
* gnu/system/vm.scm (qemu-image, system-qemu-image): Likewise.
* tests/builders.scm, tests/derivations.scm, tests/packages.scm,
  tests/store.scm, tests/union.scm: Adjust to the new calling
  convention.
* doc/guix.texi (Defining Packages, The Store, Derivations): Adjust
  accordingly.

1 files changed, 11 insertions, 12 deletions

diff --git a/guix/scripts/build.scm b/guix/scripts/build.scm
index 26cd28215e..a06755dc7a 100644
--- a/guix/scripts/build.scm
+++ b/guix/scripts/build.scm
@@ -250,7 +250,7 @@ Build the given PACKAGE-OR-DERIVATION and return their output paths.\n"))
                                    (derivations-from-package-expressions
                                     str package->derivation sys src?))
                                   (('argument . (? derivation-path? drv))
-                                   drv)
+                                   (call-with-input-file drv read-derivation))
                                   (('argument . (? string? x))
                                    (let ((p (find-package x)))
                                      (if src?
@@ -280,24 +280,23 @@ Build the given PACKAGE-OR-DERIVATION and return their output paths.\n"))
 
           (if (assoc-ref opts 'derivations-only?)
               (begin
-                (format #t "~{~a~%~}" drv)
+                (format #t "~{~a~%~}" (map derivation-file-name drv))
                 (for-each (cut register-root <> <>)
-                          (map list drv) roots))
+                          (map (compose list derivation-file-name) drv)
+                          roots))
               (or (assoc-ref opts 'dry-run?)
                   (and (build-derivations (%store) drv)
                        (for-each (lambda (d)
-                                   (let ((drv (call-with-input-file d
-                                                read-derivation)))
-                                     (format #t "~{~a~%~}"
-                                             (map (match-lambda
-                                                   ((out-name . out)
-                                                    (derivation-path->output-path
-                                                     d out-name)))
-                                                  (derivation-outputs drv)))))
+                                   (format #t "~{~a~%~}"
+                                           (map (match-lambda
+                                                 ((out-name . out)
+                                                  (derivation->output-path
+                                                   d out-name)))
+                                                (derivation-outputs d))))
                                  drv)
                        (for-each (cut register-root <> <>)
                                  (map (lambda (drv)
                                         (map cdr
-                                             (derivation-path->output-paths drv)))
+                                             (derivation->output-paths drv)))
                                       drv)
                                  roots)))))))))