diff --git a/guix/build-system/cargo.scm b/guix/build-system/cargo.scm
index 0af0ce0233..60c35eed07 100644
--- a/guix/build-system/cargo.scm
+++ b/guix/build-system/cargo.scm
@@ -114,13 +114,8 @@ (define builder
                        #:phases #$(if (pair? phases)
                                       (sexp->gexp phases)
                                       phases)
-                       #:outputs (list #$@(map (lambda (name)
-                                                 #~(cons #$name
-                                                         (ungexp output name)))
-                                               outputs))
-                       #:inputs (map (lambda (tuple)
-                                       (apply cons tuple))
-                                     '#$inputs)
+                       #:outputs #$(outputs->gexp outputs)
+                       #:inputs #$(input-tuples->gexp inputs)
                        #:search-paths '#$(sexp->gexp
                                           (map search-path-specification->sexp
                                                search-paths))))))
diff --git a/guix/build-system/cmake.scm b/guix/build-system/cmake.scm
index 80059217c2..2f9689b07c 100644
--- a/guix/build-system/cmake.scm
+++ b/guix/build-system/cmake.scm
@@ -204,20 +204,14 @@ (define builder
           (use-modules #$@(sexp->gexp modules))
 
           (define %build-host-inputs
-            (map (lambda (tuple)
-                   (apply cons tuple))
-                 '#+(append build-inputs target-inputs)))
+            #+(input-tuples->gexp build-inputs))
 
           (define %build-target-inputs
-            (map (lambda (tuple)
-                   (apply cons tuple))
-                 '#$host-inputs))
+            (append #$(input-tuples->gexp host-inputs)
+                    #+(input-tuples->gexp target-inputs)))
 
           (define %outputs
-            (list #$@(map (lambda (name)
-                            #~(cons #$name
-                                    (ungexp output name)))
-                          outputs)))
+            #$(outputs->gexp outputs))
 
           (cmake-build #:source #+source
                        #:system #$system
diff --git a/guix/build-system/gnu.scm b/guix/build-system/gnu.scm
index 3fb1a241dd..a1b2b654aa 100644
--- a/guix/build-system/gnu.scm
+++ b/guix/build-system/gnu.scm
@@ -510,20 +510,14 @@ (define builder
         (use-modules #$@(sexp->gexp modules))
 
         (define %build-host-inputs
-          (map (lambda (tuple)
-                 (apply cons tuple))
-               '#+build-inputs))
+          #+(input-tuples->gexp build-inputs))
 
         (define %build-target-inputs
-          (map (lambda (tuple)
-                 (apply cons tuple))
-               (append '#$host-inputs '#+target-inputs)))
+          (append #$(input-tuples->gexp host-inputs)
+                  #+(input-tuples->gexp target-inputs)))
 
         (define %outputs
-          (list #$@(map (lambda (name)
-                          #~(cons #$name
-                                  (ungexp output name)))
-                        outputs)))
+          #$(outputs->gexp outputs))
 
         (gnu-build #:source #+source
                    #:system #$system
diff --git a/guix/build-system/ocaml.scm b/guix/build-system/ocaml.scm
index 2f60f0d534..e7d6d96f0e 100644
--- a/guix/build-system/ocaml.scm
+++ b/guix/build-system/ocaml.scm
@@ -260,13 +260,8 @@ (define builder
           (use-modules #$@modules)
           (ocaml-build #:source #$source
                        #:system #$system
-                       #:outputs (list #$@(map (lambda (name)
-                                                 #~(cons #$name
-                                                         (ungexp output name)))
-                                               outputs))
-                       #:inputs (map (lambda (tuple)
-                                       (apply cons tuple))
-                                     '#$inputs)
+                       #:outputs #$(outputs->gexp outputs)
+                       #:inputs #$(input-tuples->gexp inputs)
                        #:search-paths '#$(map search-path-specification->sexp
                                               search-paths)
                        #:phases #$phases
diff --git a/guix/gexp.scm b/guix/gexp.scm
index 526a21fdd7..edd1224aa9 100644
--- a/guix/gexp.scm
+++ b/guix/gexp.scm
@@ -106,6 +106,9 @@ (define-module (guix gexp)
             lowered-gexp-load-compiled-path
 
             with-build-variables
+            input-tuples->gexp
+            outputs->gexp
+
             gexp->derivation
             gexp->file
             gexp->script