packages: Mark the `arguments' field of <package> as thunked.

* guix/packages.scm (<package>): Mark `arguments' as thunked.
  (package-derivation): Adjust accordingly.  Parameterize
  %CURRENT-SYSTEM to SYSTEM, so that arguments can refer to it.

* guix/build-system/gnu.scm (package-with-explicit-inputs): Expect
  `package-arguments' to always return a list, and return a list.
  (package-with-extra-configure-variable): Likewise.
  (static-package): Likewise.
* gnu/packages/base.scm (patch, findutils, gcc-4.7, binutils-boot0,
  gcc-boot0, glibc-final-with-bootstrap-bash, cross-gcc-wrapper,
  static-bash-for-glibc, binutils-final, gcc-final): Change `arguments'
  from a lambda to a list, and use (%current-system) as needed.
  (nix-system->gnu-triplet, boot-triplet): Have the first argument
  default to (%current-system).
* gnu/packages/bootstrap.scm (glibc-dynamic-linker): Have `system'
  default to (%current-system).
  (%bootstrap-gcc): Change `arguments' to a list.
* gnu/packages/gawk.scm (gawk): Likewise.
* gnu/packages/m4.scm (m4): Likewise.
* gnu/packages/make-bootstrap.scm (%glibc-for-bootstrap): Likewise, and
  expect `package-arguments' to return a list.
  (%static-inputs, %gcc-static, tarball-package): Likewise.
* gnu/packages/ncurses.scm (ncurses): Likewise.

8 files changed, 432 insertions, 474 deletions

diff --git a/gnu/packages/base.scm b/gnu/packages/base.scm
index 4764039afd..23bf00b241 100644
--- a/gnu/packages/base.scm
+++ b/gnu/packages/base.scm
@@ -162,10 +162,10 @@ files (as archives).")
    (build-system gnu-build-system)
    (native-inputs '())                      ; FIXME: needs `ed' for the tests
    (arguments
-    (case-lambda
-      ((system) '(#:tests? #f))
-      ((system cross-system)
-       '(#:configure-flags '("ac_cv_func_strnlen_working=yes")))))
+    '(#:tests? #f)
+    ;; TODO: When cross-compiling, add this:
+    ;;  '(#:configure-flags '("ac_cv_func_strnlen_working=yes"))
+    )
    (synopsis "GNU Patch, a program to apply differences to files")
    (description
     "GNU Patch takes a patch file containing a difference listing produced by
@@ -235,14 +235,13 @@ You can use the sdiff command to merge two files interactively.")
     `(("patch/absolute-paths"
        ,(search-patch "findutils-absolute-paths.patch"))))
    (arguments
-    (case-lambda
-      ((system)
-       `(#:patches (list (assoc-ref %build-inputs "patch/absolute-paths"))))
-      ((system cross-system)
-       ;; Work around cross-compilation failure.
-       ;; See <http://savannah.gnu.org/bugs/?27299#comment1>.
-       `(#:configure-flags '("gl_cv_func_wcwidth_works=yes")
-         ,@(arguments cross-system)))))
+    `(#:patches (list (assoc-ref %build-inputs "patch/absolute-paths")))
+
+    ;; TODO: Work around cross-compilation failure.
+    ;; See <http://savannah.gnu.org/bugs/?27299#comment1>.
+    ;; `(#:configure-flags '("gl_cv_func_wcwidth_works=yes")
+    ;;   ,@(arguments cross-system))
+    )
    (synopsis "Basic directory searching utilities of the GNU operating
 system")
    (description
@@ -396,90 +395,89 @@ BFD (Binary File Descriptor) library, `gprof', `nm', `strip', etc.")
                ("mpfr" ,mpfr)
                ("mpc" ,mpc)))           ; TODO: libelf, ppl, cloog, zlib, etc.
      (arguments
-      (lambda (system)
-        `(#:out-of-source? #t
-          #:strip-binaries? ,stripped?
-          #:configure-flags
-          `("--enable-plugin"
-            "--enable-languages=c,c++"
-            "--disable-multilib"
-
-            "--with-local-prefix=/no-gcc-local-prefix"
-
-            ,(let ((libc (assoc-ref %build-inputs "libc")))
-               (if libc
-                   (string-append "--with-native-system-header-dir=" libc
-                                  "/include")
-                   "--without-headers")))
-          #:make-flags
-          (let ((libc (assoc-ref %build-inputs "libc")))
-            `(,@(if libc
-                    (list (string-append "LDFLAGS_FOR_BUILD="
-                                         "-L" libc "/lib "
-                                         "-Wl,-dynamic-linker "
-                                         "-Wl," libc
-                                         ,(glibc-dynamic-linker system)))
-                    '())
-              ,(string-append "BOOT_CFLAGS=-O2 "
-                              ,(if stripped? "-g0" "-g"))))
-
-          #:tests? #f
-          #:phases
-          (alist-cons-before
-           'configure 'pre-configure
-           (lambda* (#:key inputs outputs #:allow-other-keys)
-             (let ((out  (assoc-ref outputs "out"))
-                   (libc (assoc-ref inputs "libc")))
-               (when libc
-                 ;; The following is not performed for `--without-headers'
-                 ;; cross-compiler builds.
-
-                 ;; Fix the dynamic linker's file name.
-                 (substitute* (find-files "gcc/config"
-                                          "^linux(64|-elf)?\\.h$")
-                   (("#define GLIBC_DYNAMIC_LINKER([^ ]*).*$" _ suffix)
-                    (format #f "#define GLIBC_DYNAMIC_LINKER~a \"~a\"~%"
-                            suffix
-                            (string-append libc ,(glibc-dynamic-linker system)))))
-
-                 ;; Tell where to find libstdc++, libc, and `?crt*.o', except
-                 ;; `crt{begin,end}.o', which come with GCC.
-                 (substitute* (find-files "gcc/config"
-                                          "^(gnu-user(64)?|linux-elf)\\.h$")
-                   (("#define LIB_SPEC (.*)$" _ suffix)
-                    ;; Note that with this "lib" spec, we may still add a
-                    ;; RUNPATH to GCC even when `libgcc_s' is not NEEDED.
-                    ;; There's not much that can be done to avoid it, though.
-                    (format #f "#define LIB_SPEC \"-L~a/lib %{!static:-rpath=~a/lib \
+      `(#:out-of-source? #t
+        #:strip-binaries? ,stripped?
+        #:configure-flags
+        `("--enable-plugin"
+          "--enable-languages=c,c++"
+          "--disable-multilib"
+
+          "--with-local-prefix=/no-gcc-local-prefix"
+
+          ,(let ((libc (assoc-ref %build-inputs "libc")))
+             (if libc
+                 (string-append "--with-native-system-header-dir=" libc
+                                "/include")
+                 "--without-headers")))
+        #:make-flags
+        (let ((libc (assoc-ref %build-inputs "libc")))
+          `(,@(if libc
+                  (list (string-append "LDFLAGS_FOR_BUILD="
+                                       "-L" libc "/lib "
+                                       "-Wl,-dynamic-linker "
+                                       "-Wl," libc
+                                       ,(glibc-dynamic-linker)))
+                  '())
+            ,(string-append "BOOT_CFLAGS=-O2 "
+                            ,(if stripped? "-g0" "-g"))))
+
+        #:tests? #f
+        #:phases
+        (alist-cons-before
+         'configure 'pre-configure
+         (lambda* (#:key inputs outputs #:allow-other-keys)
+           (let ((out  (assoc-ref outputs "out"))
+                 (libc (assoc-ref inputs "libc")))
+             (when libc
+               ;; The following is not performed for `--without-headers'
+               ;; cross-compiler builds.
+
+               ;; Fix the dynamic linker's file name.
+               (substitute* (find-files "gcc/config"
+                                        "^linux(64|-elf)?\\.h$")
+                 (("#define GLIBC_DYNAMIC_LINKER([^ ]*).*$" _ suffix)
+                  (format #f "#define GLIBC_DYNAMIC_LINKER~a \"~a\"~%"
+                          suffix
+                          (string-append libc ,(glibc-dynamic-linker)))))
+
+               ;; Tell where to find libstdc++, libc, and `?crt*.o', except
+               ;; `crt{begin,end}.o', which come with GCC.
+               (substitute* (find-files "gcc/config"
+                                        "^(gnu-user(64)?|linux-elf)\\.h$")
+                 (("#define LIB_SPEC (.*)$" _ suffix)
+                  ;; Note that with this "lib" spec, we may still add a
+                  ;; RUNPATH to GCC even when `libgcc_s' is not NEEDED.
+                  ;; There's not much that can be done to avoid it, though.
+                  (format #f "#define LIB_SPEC \"-L~a/lib %{!static:-rpath=~a/lib \
 %{!static-libgcc:-rpath=~a/lib64 -rpath=~a/lib}} \" ~a~%"
-                            libc libc out out suffix))
-                   (("#define STARTFILE_SPEC.*$" line)
-                    (format #f "#define STANDARD_STARTFILE_PREFIX_1 \"~a/lib\"
+                          libc libc out out suffix))
+                 (("#define STARTFILE_SPEC.*$" line)
+                  (format #f "#define STANDARD_STARTFILE_PREFIX_1 \"~a/lib\"
 #define STANDARD_STARTFILE_PREFIX_2 \"\"
 ~a~%"
-                            libc line))))
-
-               ;; Don't retain a dependency on the build-time sed.
-               (substitute* "fixincludes/fixincl.x"
-                 (("static char const sed_cmd_z\\[\\] =.*;")
-                  "static char const sed_cmd_z[] = \"sed\";"))))
-
-           (alist-cons-after
-            'configure 'post-configure
-            (lambda _
-              ;; Don't store configure flags, to avoid retaining references to
-              ;; build-time dependencies---e.g., `--with-ppl=/nix/store/xxx'.
-              (substitute* "Makefile"
-                (("^TOPLEVEL_CONFIGURE_ARGUMENTS=(.*)$" _ rest)
-                 "TOPLEVEL_CONFIGURE_ARGUMENTS=\n")))
-            (alist-replace 'install
-                           (lambda* (#:key outputs #:allow-other-keys)
-                             (zero?
-                              (system* "make"
-                                       ,(if stripped?
-                                            "install-strip"
-                                            "install"))))
-                           %standard-phases))))))
+                          libc line))))
+
+             ;; Don't retain a dependency on the build-time sed.
+             (substitute* "fixincludes/fixincl.x"
+               (("static char const sed_cmd_z\\[\\] =.*;")
+                "static char const sed_cmd_z[] = \"sed\";"))))
+
+         (alist-cons-after
+          'configure 'post-configure
+          (lambda _
+            ;; Don't store configure flags, to avoid retaining references to
+            ;; build-time dependencies---e.g., `--with-ppl=/nix/store/xxx'.
+            (substitute* "Makefile"
+              (("^TOPLEVEL_CONFIGURE_ARGUMENTS=(.*)$" _ rest)
+               "TOPLEVEL_CONFIGURE_ARGUMENTS=\n")))
+          (alist-replace 'install
+                         (lambda* (#:key outputs #:allow-other-keys)
+                           (zero?
+                            (system* "make"
+                                     ,(if stripped?
+                                          "install-strip"
+                                          "install"))))
+                         %standard-phases)))))
 
      (properties `((gcc-libc . ,(assoc-ref inputs "libc"))))
      (synopsis "The GNU Compiler Collection")
@@ -653,7 +651,8 @@ with the Linux kernel.")
     ("findutils" ,findutils-boot0)
     ,@%bootstrap-inputs))
 
-(define* (nix-system->gnu-triplet system #:optional (vendor "unknown"))
+(define* (nix-system->gnu-triplet
+          #:optional (system (%current-system)) (vendor "unknown"))
   "Return an a guess of the GNU triplet corresponding to Nix system
 identifier SYSTEM."
   (let* ((dash (string-index system #\-))
@@ -665,10 +664,10 @@ identifier SYSTEM."
                        "linux-gnu"
                        os))))
 
-(define boot-triplet
+(define* (boot-triplet #:optional (system (%current-system)))
   ;; Return the triplet used to create the cross toolchain needed in the
   ;; first bootstrapping stage.
-  (cut nix-system->gnu-triplet <> "guix"))
+  (nix-system->gnu-triplet system "guix"))
 
 ;; Following Linux From Scratch, build a cross-toolchain in stage 0.  That
 ;; toolchain actually targets the same OS and arch, but it has the advantage
@@ -680,12 +679,11 @@ identifier SYSTEM."
    (package (inherit binutils)
      (name "binutils-cross-boot0")
      (arguments
-      (lambda (system)
-        `(#:guile ,%bootstrap-guile
-          #:implicit-inputs? #f
-          ,@(substitute-keyword-arguments (package-arguments binutils)
-              ((#:configure-flags cf)
-               `(list ,(string-append "--target=" (boot-triplet system))))))))
+      `(#:guile ,%bootstrap-guile
+        #:implicit-inputs? #f
+        ,@(substitute-keyword-arguments (package-arguments binutils)
+            ((#:configure-flags cf)
+             `(list ,(string-append "--target=" (boot-triplet)))))))
      (inputs %boot0-inputs))))
 
 (define gcc-boot0
@@ -693,82 +691,80 @@ identifier SYSTEM."
    (package (inherit gcc-4.7)
      (name "gcc-cross-boot0")
      (arguments
-      (lambda (system)
-        `(#:guile ,%bootstrap-guile
-          #:implicit-inputs? #f
-          #:modules ((guix build gnu-build-system)
-                     (guix build utils)
-                     (ice-9 regex)
-                     (srfi srfi-1)
-                     (srfi srfi-26))
-          ,@(substitute-keyword-arguments ((package-arguments gcc-4.7) system)
-              ((#:configure-flags flags)
-               `(append (list ,(string-append "--target="
-                                              (boot-triplet system))
-
-                              ;; No libc yet.
-                              "--without-headers"
-
-                              ;; Disable features not needed at this stage.
-                              "--disable-shared"
-                              "--enable-languages=c"
-                              "--disable-libmudflap"
-                              "--disable-libgomp"
-                              "--disable-libssp"
-                              "--disable-libquadmath"
-                              "--disable-decimal-float")
-                        (remove (cut string-match "--enable-languages.*" <>)
-                                ,flags)))
-              ((#:phases phases)
-               `(alist-cons-after
-                 'unpack 'unpack-gmp&co
-                 (lambda* (#:key inputs #:allow-other-keys)
-                   (let ((gmp  (assoc-ref %build-inputs "gmp-source"))
-                         (mpfr (assoc-ref %build-inputs "mpfr-source"))
-                         (mpc  (assoc-ref %build-inputs "mpc-source")))
-
-                     ;; To reduce the set of pre-built bootstrap inputs, build
-                     ;; GMP & co. from GCC.
-                     (for-each (lambda (source)
-                                 (or (zero? (system* "tar" "xvf" source))
-                                     (error "failed to unpack tarball"
-                                            source)))
-                               (list gmp mpfr mpc))
-
-                     ;; Create symlinks like `gmp' -> `gmp-5.0.5'.
-                     ,@(map (lambda (lib)
-                              `(symlink ,(package-full-name lib)
-                                        ,(package-name lib)))
-                            (list gmp mpfr mpc))
-
-                     ;; MPFR headers/lib are found under $(MPFR)/src, but
-                     ;; `configure' wrongfully tells MPC too look under
-                     ;; $(MPFR), so fix that.
-                     (substitute* "configure"
-                       (("extra_mpc_mpfr_configure_flags(.+)--with-mpfr-include=([^/]+)/mpfr(.*)--with-mpfr-lib=([^ ]+)/mpfr"
-                         _ equals include middle lib)
-                        (string-append "extra_mpc_mpfr_configure_flags" equals
-                                       "--with-mpfr-include=" include
-                                       "/mpfr/src" middle
-                                       "--with-mpfr-lib=" lib
-                                       "/mpfr/src"))
-                       (("gmpinc='-I([^ ]+)/mpfr -I([^ ]+)/mpfr" _ a b)
-                        (string-append "gmpinc='-I" a "/mpfr/src "
-                                       "-I" b "/mpfr/src"))
-                       (("gmplibs='-L([^ ]+)/mpfr" _ a)
-                        (string-append "gmplibs='-L" a "/mpfr/src")))))
-                 (alist-cons-after
-                  'install 'symlink-libgcc_eh
-                  (lambda* (#:key outputs #:allow-other-keys)
-                    (let ((out (assoc-ref outputs "out")))
-                      ;; Glibc wants to link against libgcc_eh, so provide
-                      ;; it.
-                      (with-directory-excursion
-                          (string-append out "/lib/gcc/"
-                                         ,(boot-triplet system)
-                                         "/" ,(package-version gcc-4.7))
-                        (symlink "libgcc.a" "libgcc_eh.a"))))
-                  ,phases)))))))
+      `(#:guile ,%bootstrap-guile
+        #:implicit-inputs? #f
+        #:modules ((guix build gnu-build-system)
+                   (guix build utils)
+                   (ice-9 regex)
+                   (srfi srfi-1)
+                   (srfi srfi-26))
+        ,@(substitute-keyword-arguments (package-arguments gcc-4.7)
+            ((#:configure-flags flags)
+             `(append (list ,(string-append "--target=" (boot-triplet))
+
+                            ;; No libc yet.
+                            "--without-headers"
+
+                            ;; Disable features not needed at this stage.
+                            "--disable-shared"
+                            "--enable-languages=c"
+                            "--disable-libmudflap"
+                            "--disable-libgomp"
+                            "--disable-libssp"
+                            "--disable-libquadmath"
+                            "--disable-decimal-float")
+                      (remove (cut string-match "--enable-languages.*" <>)
+                              ,flags)))
+            ((#:phases phases)
+             `(alist-cons-after
+               'unpack 'unpack-gmp&co
+               (lambda* (#:key inputs #:allow-other-keys)
+                 (let ((gmp  (assoc-ref %build-inputs "gmp-source"))
+                       (mpfr (assoc-ref %build-inputs "mpfr-source"))
+                       (mpc  (assoc-ref %build-inputs "mpc-source")))
+
+                   ;; To reduce the set of pre-built bootstrap inputs, build
+                   ;; GMP & co. from GCC.
+                   (for-each (lambda (source)
+                               (or (zero? (system* "tar" "xvf" source))
+                                   (error "failed to unpack tarball"
+                                          source)))
+                             (list gmp mpfr mpc))
+
+                   ;; Create symlinks like `gmp' -> `gmp-5.0.5'.
+                   ,@(map (lambda (lib)
+                            `(symlink ,(package-full-name lib)
+                                      ,(package-name lib)))
+                          (list gmp mpfr mpc))
+
+                   ;; MPFR headers/lib are found under $(MPFR)/src, but
+                   ;; `configure' wrongfully tells MPC too look under
+                   ;; $(MPFR), so fix that.
+                   (substitute* "configure"
+                     (("extra_mpc_mpfr_configure_flags(.+)--with-mpfr-include=([^/]+)/mpfr(.*)--with-mpfr-lib=([^ ]+)/mpfr"
+                       _ equals include middle lib)
+                      (string-append "extra_mpc_mpfr_configure_flags" equals
+                                     "--with-mpfr-include=" include
+                                     "/mpfr/src" middle
+                                     "--with-mpfr-lib=" lib
+                                     "/mpfr/src"))
+                     (("gmpinc='-I([^ ]+)/mpfr -I([^ ]+)/mpfr" _ a b)
+                      (string-append "gmpinc='-I" a "/mpfr/src "
+                                     "-I" b "/mpfr/src"))
+                     (("gmplibs='-L([^ ]+)/mpfr" _ a)
+                      (string-append "gmplibs='-L" a "/mpfr/src")))))
+               (alist-cons-after
+                'install 'symlink-libgcc_eh
+                (lambda* (#:key outputs #:allow-other-keys)
+                  (let ((out (assoc-ref outputs "out")))
+                    ;; Glibc wants to link against libgcc_eh, so provide
+                    ;; it.
+                    (with-directory-excursion
+                        (string-append out "/lib/gcc/"
+                                       ,(boot-triplet)
+                                       "/" ,(package-version gcc-4.7))
+                      (symlink "libgcc.a" "libgcc_eh.a"))))
+                ,phases))))))
 
      (inputs `(("gmp-source" ,(package-source gmp))
                ("mpfr-source" ,(package-source mpfr))
@@ -812,20 +808,19 @@ identifier SYSTEM."
    (package (inherit glibc)
      (name "glibc-intermediate")
      (arguments
-      (lambda (system)
-        `(#:guile ,%bootstrap-guile
-          #:implicit-inputs? #f
-
-          ,@(substitute-keyword-arguments (package-arguments glibc)
-              ((#:configure-flags flags)
-               `(append (list ,(string-append "--host=" (boot-triplet system))
-                              ,(string-append "--build="
-                                              (nix-system->gnu-triplet system))
-
-                              ;; Build Sun/ONC RPC support.  In particular,
-                              ;; install rpc/*.h.
-                              "--enable-obsolete-rpc")
-                        ,flags))))))
+      `(#:guile ,%bootstrap-guile
+        #:implicit-inputs? #f
+
+        ,@(substitute-keyword-arguments (package-arguments glibc)
+            ((#:configure-flags flags)
+             `(append (list ,(string-append "--host=" (boot-triplet))
+                            ,(string-append "--build="
+                                            (nix-system->gnu-triplet))
+
+                            ;; Build Sun/ONC RPC support.  In particular,
+                            ;; install rpc/*.h.
+                            "--enable-obsolete-rpc")
+                      ,flags)))))
      (propagated-inputs `(("linux-headers" ,linux-libre-headers-boot0)))
      (inputs
       `( ;; A native GCC is needed to build `cross-rpcgen'.
@@ -847,40 +842,39 @@ that makes it available under the native tool names."
     (source #f)
     (build-system trivial-build-system)
     (arguments
-     (lambda (system)
-       `(#:guile ,%bootstrap-guile
-         #:modules ((guix build utils))
-         #:builder (begin
-                     (use-modules (guix build utils))
-
-                     (let* ((binutils (assoc-ref %build-inputs "binutils"))
-                            (gcc      (assoc-ref %build-inputs "gcc"))
-                            (libc     (assoc-ref %build-inputs "libc"))
-                            (bash     (assoc-ref %build-inputs "bash"))
-                            (out      (assoc-ref %outputs "out"))
-                            (bindir   (string-append out "/bin"))
-                            (triplet  ,(boot-triplet system)))
-                       (mkdir-p bindir)
-                       (with-directory-excursion bindir
-                         (for-each (lambda (tool)
-                                     (symlink (string-append binutils "/bin/"
-                                                             triplet "-" tool)
-                                              tool))
-                                   '("ar" "ranlib"))
-
-                         ;; GCC-BOOT0 is a libc-less cross-compiler, so it
-                         ;; needs to be told where to find the crt files and
-                         ;; the dynamic linker.
-                         (call-with-output-file "gcc"
-                           (lambda (p)
-                             (format p "#!~a/bin/bash
+     `(#:guile ,%bootstrap-guile
+       #:modules ((guix build utils))
+       #:builder (begin
+                   (use-modules (guix build utils))
+
+                   (let* ((binutils (assoc-ref %build-inputs "binutils"))
+                          (gcc      (assoc-ref %build-inputs "gcc"))
+                          (libc     (assoc-ref %build-inputs "libc"))
+                          (bash     (assoc-ref %build-inputs "bash"))
+                          (out      (assoc-ref %outputs "out"))
+                          (bindir   (string-append out "/bin"))
+                          (triplet  ,(boot-triplet)))
+                     (mkdir-p bindir)
+                     (with-directory-excursion bindir
+                       (for-each (lambda (tool)
+                                   (symlink (string-append binutils "/bin/"
+                                                           triplet "-" tool)
+                                            tool))
+                                 '("ar" "ranlib"))
+
+                       ;; GCC-BOOT0 is a libc-less cross-compiler, so it
+                       ;; needs to be told where to find the crt files and
+                       ;; the dynamic linker.
+                       (call-with-output-file "gcc"
+                         (lambda (p)
+                           (format p "#!~a/bin/bash
 exec ~a/bin/~a-gcc -B~a/lib -Wl,-dynamic-linker -Wl,~a/~a \"$@\"~%"
-                                     bash
-                                     gcc triplet
-                                     libc libc
-                                     ,(glibc-dynamic-linker system))))
+                                   bash
+                                   gcc triplet
+                                   libc libc
+                                   ,(glibc-dynamic-linker))))
 
-                         (chmod "gcc" #o555)))))))
+                       (chmod "gcc" #o555))))))
     (native-inputs
      `(("binutils" ,binutils)
        ("gcc" ,gcc)
@@ -896,9 +890,8 @@ exec ~a/bin/~a-gcc -B~a/lib -Wl,-dynamic-linker -Wl,~a/~a \"$@\"~%"
                                   (car (assoc-ref %boot1-inputs "bash"))))
          (bash (package (inherit bash-light)
                  (arguments
-                  (lambda (system)
-                    `(#:guile ,%bootstrap-guile
-                      ,@(package-arguments bash-light)))))))
+                  `(#:guile ,%bootstrap-guile
+                    ,@(package-arguments bash-light))))))
     (package-with-bootstrap-guile
      (package-with-explicit-inputs (static-package bash)
                                    `(("gcc" ,gcc)
@@ -932,10 +925,9 @@ exec ~a/bin/~a-gcc -B~a/lib -Wl,-dynamic-linker -Wl,~a/~a \"$@\"~%"
   (package-with-bootstrap-guile
    (package (inherit binutils)
      (arguments
-      (lambda (system)
-        `(#:guile ,%bootstrap-guile
-                  #:implicit-inputs? #f
-                  ,@(package-arguments binutils))))
+      `(#:guile ,%bootstrap-guile
+        #:implicit-inputs? #f
+        ,@(package-arguments binutils)))
      (inputs %boot2-inputs))))
 
 (define-public gcc-final
@@ -943,23 +935,22 @@ exec ~a/bin/~a-gcc -B~a/lib -Wl,-dynamic-linker -Wl,~a/~a \"$@\"~%"
   (package (inherit gcc-boot0)
     (name "gcc")
     (arguments
-     (lambda (system)
-       `(#:guile ,%bootstrap-guile
-         #:implicit-inputs? #f
-
-         ;; Build again GMP & co. within GCC's build process, because it's hard
-         ;; to do outside (because GCC-BOOT0 is a cross-compiler, and thus
-         ;; doesn't honor $LIBRARY_PATH, which breaks `gnu-build-system'.)
-         ,@(substitute-keyword-arguments ((package-arguments gcc-boot0) system)
-             ((#:configure-flags boot-flags)
-              (let loop ((args ((package-arguments gcc-4.7) system)))
-                (match args
-                  ((#:configure-flags normal-flags _ ...)
-                   normal-flags)
-                  ((_ rest ...)
-                   (loop rest)))))
-             ((#:phases phases)
-              `(alist-delete 'symlink-libgcc_eh ,phases))))))
+     `(#:guile ,%bootstrap-guile
+       #:implicit-inputs? #f
+
+       ;; Build again GMP & co. within GCC's build process, because it's hard
+       ;; to do outside (because GCC-BOOT0 is a cross-compiler, and thus
+       ;; doesn't honor $LIBRARY_PATH, which breaks `gnu-build-system'.)
+       ,@(substitute-keyword-arguments (package-arguments gcc-boot0)
+           ((#:configure-flags boot-flags)
+            (let loop ((args (package-arguments gcc-4.7)))
+              (match args
+                ((#:configure-flags normal-flags _ ...)
+                 normal-flags)
+                ((_ rest ...)
+                 (loop rest)))))
+           ((#:phases phases)
+            `(alist-delete 'symlink-libgcc_eh ,phases)))))
 
     (inputs `(("gmp-source" ,(package-source gmp))
               ("mpfr-source" ,(package-source mpfr))
diff --git a/gnu/packages/bootstrap.scm b/gnu/packages/bootstrap.scm
index 39cdea2f62..ea2cf618f2 100644
--- a/gnu/packages/bootstrap.scm
+++ b/gnu/packages/bootstrap.scm
@@ -133,7 +133,7 @@ check whether everything is alright."
       (propagated-inputs (map rewritten-input
                               (package-propagated-inputs p)))))))
 
-(define (glibc-dynamic-linker system)
+(define* (glibc-dynamic-linker #:optional (system (%current-system)))
   "Return the name of Glibc's dynamic linker for SYSTEM."
   (cond ((string=? system "x86_64-linux") "/lib/ld-linux-x86-64.so.2")
         ((string=? system "i686-linux") "/lib/ld-linux.so.2")
@@ -301,42 +301,41 @@ $out/bin/guile --version~%"
     (source #f)
     (build-system trivial-build-system)
     (arguments
-     (lambda (system)
-       `(#:guile ,%bootstrap-guile
-         #:modules ((guix build utils))
-         #:builder
-         (let ((out     (assoc-ref %outputs "out"))
-               (tar     (assoc-ref %build-inputs "tar"))
-               (xz      (assoc-ref %build-inputs "xz"))
-               (bash    (assoc-ref %build-inputs "bash"))
-               (libc    (assoc-ref %build-inputs "libc"))
-               (tarball (assoc-ref %build-inputs "tarball")))
-           (use-modules (guix build utils)
-                        (ice-9 popen))
+     `(#:guile ,%bootstrap-guile
+       #:modules ((guix build utils))
+       #:builder
+       (let ((out     (assoc-ref %outputs "out"))
+             (tar     (assoc-ref %build-inputs "tar"))
+             (xz      (assoc-ref %build-inputs "xz"))
+             (bash    (assoc-ref %build-inputs "bash"))
+             (libc    (assoc-ref %build-inputs "libc"))
+             (tarball (assoc-ref %build-inputs "tarball")))
+         (use-modules (guix build utils)
+                      (ice-9 popen))
 
-           (mkdir out)
-           (copy-file tarball "binaries.tar.xz")
-           (system* xz "-d" "binaries.tar.xz")
-           (let ((builddir (getcwd))
-                 (bindir   (string-append out "/bin")))
-             (with-directory-excursion out
-               (system* tar "xvf"
-                        (string-append builddir "/binaries.tar")))
+         (mkdir out)
+         (copy-file tarball "binaries.tar.xz")
+         (system* xz "-d" "binaries.tar.xz")
+         (let ((builddir (getcwd))
+               (bindir   (string-append out "/bin")))
+           (with-directory-excursion out
+             (system* tar "xvf"
+                      (string-append builddir "/binaries.tar")))
 
-             (with-directory-excursion bindir
-               (chmod "." #o755)
-               (rename-file "gcc" ".gcc-wrapped")
-               (call-with-output-file "gcc"
-                 (lambda (p)
-                   (format p "#!~a
+           (with-directory-excursion bindir
+             (chmod "." #o755)
+             (rename-file "gcc" ".gcc-wrapped")
+             (call-with-output-file "gcc"
+               (lambda (p)
+                 (format p "#!~a
 exec ~a/bin/.gcc-wrapped -B~a/lib \
      -Wl,-rpath -Wl,~a/lib \
      -Wl,-dynamic-linker -Wl,~a/~a \"$@\"~%"
-                           bash
-                           out libc libc libc
-                           ,(glibc-dynamic-linker system))))
+                         bash
+                         out libc libc libc
+                         ,(glibc-dynamic-linker))))
 
-               (chmod "gcc" #o555)))))))
+             (chmod "gcc" #o555))))))
     (inputs
      `(("tar" ,(lambda (system)
                  (search-bootstrap-binary "tar" system)))
diff --git a/gnu/packages/gawk.scm b/gnu/packages/gawk.scm
index 802042665a..ad87043d96 100644
--- a/gnu/packages/gawk.scm
+++ b/gnu/packages/gawk.scm
@@ -36,24 +36,20 @@
              (base32 "0sss7rhpvizi2a88h6giv0i7w5h07s2fxkw3s6n1hqvcnhrfgbb0"))))
    (build-system gnu-build-system)
    (arguments
-    (case-lambda
-      ((system)
-       `(#:parallel-tests? #f             ; test suite fails in parallel
+    `(#:parallel-tests? #f                ; test suite fails in parallel
 
-         ;; Work around test failure on Cygwin.
-         #:tests? ,(not (string=? system "i686-cygwin"))
+      ;; Work around test failure on Cygwin.
+      #:tests? ,(not (string=? (%current-system) "i686-cygwin"))
 
-         #:phases (alist-cons-before
-                   'configure 'set-shell-file-name
-                   (lambda* (#:key inputs #:allow-other-keys)
-                     ;; Refer to the right shell.
-                     (let ((bash (assoc-ref inputs "bash")))
-                       (substitute* "io.c"
-                         (("/bin/sh")
-                          (string-append bash "/bin/bash")))))
-                   %standard-phases)))
-      ((system cross-system)
-       '(#:parallel-tests? #f))))
+      #:phases (alist-cons-before
+                'configure 'set-shell-file-name
+                (lambda* (#:key inputs #:allow-other-keys)
+                  ;; Refer to the right shell.
+                  (let ((bash (assoc-ref inputs "bash")))
+                    (substitute* "io.c"
+                      (("/bin/sh")
+                       (string-append bash "/bin/bash")))))
+                %standard-phases)))
    (inputs `(("libsigsegv" ,libsigsegv)))
    (home-page "http://www.gnu.org/software/gawk/")
    (synopsis "GNU implementation of the Awk programming language")
diff --git a/gnu/packages/m4.scm b/gnu/packages/m4.scm
index fdf55f802d..2a8bc5c72c 100644
--- a/gnu/packages/m4.scm
+++ b/gnu/packages/m4.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2012, 2013 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -36,34 +36,28 @@
              (base32
               "035r7ma272j2cwni2961jp22k6bn3n9xwn3b3qbcn2yrvlghql22"))))
    (build-system gnu-build-system)
-   (arguments (case-lambda
-                ((system)
-                 ;; XXX: Disable tests on those platforms with know issues.
-                 `(#:tests? ,(not (member system
-                                          '("x86_64-darwin"
-                                            "i686-cygwin"
-                                            "i686-sunos")))
-                   #:patches (list (assoc-ref %build-inputs "patch/s_isdir")
-                                   (assoc-ref %build-inputs
-                                              "patch/readlink-EINVAL")
-                                   (assoc-ref %build-inputs "patch/gets"))
-                   #:phases (alist-cons-before
-                             'check 'pre-check
-                             (lambda* (#:key inputs #:allow-other-keys)
-                               ;; Fix references to /bin/sh.
-                               (let ((bash (assoc-ref inputs "bash")))
-                                 (for-each patch-shebang
-                                           (find-files "tests" "\\.sh$"))
-                                 (substitute* (find-files "tests"
-                                                          "posix_spawn")
-                                   (("/bin/sh")
-                                    (format #f "~a/bin/bash" bash)))))
-                             %standard-phases)))
-                ((system cross-system)
-                 `(#:patches (list (assoc-ref %build-inputs "patch/s_isdir")
-                                   (assoc-ref %build-inputs
-                                              "patch/readlink-EINVAL")
-                                   (assoc-ref %build-inputs "patch/gets"))))))
+   (arguments
+    ;; XXX: Disable tests on those platforms with know issues.
+    `(#:tests? ,(not (member (%current-system)
+                             '("x86_64-darwin"
+                               "i686-cygwin"
+                               "i686-sunos")))
+      #:patches (list (assoc-ref %build-inputs "patch/s_isdir")
+                      (assoc-ref %build-inputs
+                                 "patch/readlink-EINVAL")
+                      (assoc-ref %build-inputs "patch/gets"))
+      #:phases (alist-cons-before
+                'check 'pre-check
+                (lambda* (#:key inputs #:allow-other-keys)
+                  ;; Fix references to /bin/sh.
+                  (let ((bash (assoc-ref inputs "bash")))
+                    (for-each patch-shebang
+                              (find-files "tests" "\\.sh$"))
+                    (substitute* (find-files "tests"
+                                             "posix_spawn")
+                      (("/bin/sh")
+                       (format #f "~a/bin/bash" bash)))))
+                %standard-phases)))
    (inputs `(("patch/s_isdir" ,(search-patch "m4-s_isdir.patch"))
              ("patch/readlink-EINVAL"
               ,(search-patch "m4-readlink-EINVAL.patch"))
diff --git a/gnu/packages/make-bootstrap.scm b/gnu/packages/make-bootstrap.scm
index a252848a47..091b5c0417 100644
--- a/gnu/packages/make-bootstrap.scm
+++ b/gnu/packages/make-bootstrap.scm
@@ -52,17 +52,15 @@
   ;; without nscd, and with static NSS modules.
   (package (inherit glibc-final)
     (arguments
-     (lambda (system)
-       (substitute-keyword-arguments ((package-arguments glibc-final) system)
-         ((#:patches patches)
-          `(cons (assoc-ref %build-inputs "patch/system")
-                 ,patches))
-         ((#:configure-flags flags)
-          ;; Arrange so that getaddrinfo & co. do not contact the nscd,
-          ;; and can use statically-linked NSS modules.
-          `(cons* "--disable-nscd" "--disable-build-nscd"
-                  "--enable-static-nss"
-                  ,flags)))))
+     (substitute-keyword-arguments (package-arguments glibc-final)
+       ((#:patches patches)
+        `(cons (assoc-ref %build-inputs "patch/system") ,patches))
+       ((#:configure-flags flags)
+        ;; Arrange so that getaddrinfo & co. do not contact the nscd,
+        ;; and can use statically-linked NSS modules.
+        `(cons* "--disable-nscd" "--disable-build-nscd"
+                "--enable-static-nss"
+                ,flags))))
     (inputs
      `(("patch/system" ,(search-patch "glibc-bootstrap-system.patch"))
        ,@(package-inputs glibc-final)))))
@@ -119,19 +117,17 @@
                            %standard-phases)))))
         (gawk (package (inherit gawk)
                 (arguments
-                 (lambda (system)
-                   `(#:patches (list (assoc-ref %build-inputs "patch/sh"))
-                     ,@(substitute-keyword-arguments
-                           ((package-arguments gawk) system)
-                         ((#:phases phases)
-                          `(alist-cons-before
-                            'configure 'no-export-dynamic
-                            (lambda _
-                              ;; Since we use `-static', remove
-                              ;; `-export-dynamic'.
-                              (substitute* "configure"
-                                (("-export-dynamic") "")))
-                            ,phases))))))
+                 `(#:patches (list (assoc-ref %build-inputs "patch/sh"))
+                   ,@(substitute-keyword-arguments (package-arguments gawk)
+                       ((#:phases phases)
+                        `(alist-cons-before
+                          'configure 'no-export-dynamic
+                          (lambda _
+                            ;; Since we use `-static', remove
+                            ;; `-export-dynamic'.
+                            (substitute* "configure"
+                              (("-export-dynamic") "")))
+                          ,phases)))))
                 (inputs `(("patch/sh" ,(search-patch "gawk-shell.patch"))))))
         (finalize (lambda (p)
                     (static-package (package-with-explicit-inputs
@@ -332,29 +328,28 @@
    (package (inherit gcc-final)
      (name "gcc-static")
      (arguments
-      (lambda (system)
-        `(#:modules ((guix build utils)
-                     (guix build gnu-build-system)
-                     (srfi srfi-1)
-                     (srfi srfi-26)
-                     (ice-9 regex))
-          ,@(substitute-keyword-arguments ((package-arguments gcc-final) system)
-              ((#:guile _) #f)
-              ((#:implicit-inputs? _) #t)
-              ((#:configure-flags flags)
-               `(append (list
-                         "--disable-shared"
-                         "--disable-plugin"
-                         "--enable-languages=c"
-                         "--disable-libmudflap"
-                         "--disable-libgomp"
-                         "--disable-libssp"
-                         "--disable-libquadmath"
-                         "--disable-decimal-float")
-                        (remove (cut string-match "--(.*plugin|enable-languages)" <>)
-                                ,flags)))
-              ((#:make-flags flags)
-               `(cons "BOOT_LDFLAGS=-static" ,flags))))))
+      `(#:modules ((guix build utils)
+                   (guix build gnu-build-system)
+                   (srfi srfi-1)
+                   (srfi srfi-26)
+                   (ice-9 regex))
+        ,@(substitute-keyword-arguments (package-arguments gcc-final)
+            ((#:guile _) #f)
+            ((#:implicit-inputs? _) #t)
+            ((#:configure-flags flags)
+             `(append (list
+                       "--disable-shared"
+                       "--disable-plugin"
+                       "--enable-languages=c"
+                       "--disable-libmudflap"
+                       "--disable-libgomp"
+                       "--disable-libssp"
+                       "--disable-libquadmath"
+                       "--disable-decimal-float")
+                      (remove (cut string-match "--(.*plugin|enable-languages)" <>)
+                              ,flags)))
+            ((#:make-flags flags)
+             `(cons "BOOT_LDFLAGS=-static" ,flags)))))
      (inputs `(("gmp-source" ,(package-source gmp))
                ("mpfr-source" ,(package-source mpfr))
                ("mpc-source" ,(package-source mpc))
@@ -482,25 +477,25 @@
               ("xz" ,xz)
               ("input" ,pkg)))
     (arguments
-     (lambda (system)
-       (let ((name    (package-name pkg))
-             (version (package-version pkg)))
-         `(#:modules ((guix build utils))
-           #:builder
-           (begin
-             (use-modules (guix build utils))
-             (let ((out   (assoc-ref %outputs "out"))
-                   (input (assoc-ref %build-inputs "input"))
-                   (tar   (assoc-ref %build-inputs "tar"))
-                   (xz    (assoc-ref %build-inputs "xz")))
-               (mkdir out)
-               (set-path-environment-variable "PATH" '("bin") (list tar xz))
-               (with-directory-excursion input
-                 (zero? (system* "tar" "cJvf"
-                                 (string-append out "/"
-                                                ,name "-" ,version
-                                                "-" ,system ".tar.xz")
-                                 ".")))))))))))
+     (let ((name    (package-name pkg))
+           (version (package-version pkg)))
+       `(#:modules ((guix build utils))
+         #:builder
+         (begin
+           (use-modules (guix build utils))
+           (let ((out   (assoc-ref %outputs "out"))
+                 (input (assoc-ref %build-inputs "input"))
+                 (tar   (assoc-ref %build-inputs "tar"))
+                 (xz    (assoc-ref %build-inputs "xz")))
+             (mkdir out)
+             (set-path-environment-variable "PATH" '("bin") (list tar xz))
+             (with-directory-excursion input
+               (zero? (system* "tar" "cJvf"
+                               (string-append out "/"
+                                              ,name "-" ,version
+                                              "-" ,(%current-system)
+                                              ".tar.xz")
+                               "."))))))))))
 
 (define %bootstrap-binaries-tarball
   ;; A tarball with the statically-linked bootstrap binaries.
diff --git a/gnu/packages/ncurses.scm b/gnu/packages/ncurses.scm
index 1be2551a63..52864a6c77 100644
--- a/gnu/packages/ncurses.scm
+++ b/gnu/packages/ncurses.scm
@@ -83,34 +83,30 @@
                 "0fsn7xis81za62afan0vvm38bvgzg5wfmv1m86flqcj0nj7jjilh"))))
      (build-system gnu-build-system)
      (arguments
-      (case-lambda
-        ((system)
-         `(#:configure-flags
-           `("--with-shared" "--without-debug" "--enable-widec"
+      `(#:configure-flags
+        `("--with-shared" "--without-debug" "--enable-widec"
 
-             ;; By default headers land in an `ncursesw' subdir, which is not
-             ;; what users expect.
-             ,(string-append "--includedir=" (assoc-ref %outputs "out")
-                             "/include")
+          ;; By default headers land in an `ncursesw' subdir, which is not
+          ;; what users expect.
+          ,(string-append "--includedir=" (assoc-ref %outputs "out")
+                          "/include")
 
-             ;; C++ bindings fail to build on
-             ;; `i386-pc-solaris2.11' with GCC 3.4.3:
-             ;; <http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6395191>.
-             ,,@(if (string=? system "i686-solaris")
-                    '("--without-cxx-binding")
-                    '()))
-           #:tests? #f                            ; no "check" target
-           #:phases (alist-cons-after
-                     'install 'post-install ,post-install-phase
-                     (alist-cons-before
-                      'configure 'patch-makefile-SHELL
-                      ,patch-makefile-phase
-                      (alist-replace
-                       'configure
-                       ,configure-phase
-                       %standard-phases)))))
-        ((system cross-system)
-         (arguments cross-system))))
+          ;; C++ bindings fail to build on
+          ;; `i386-pc-solaris2.11' with GCC 3.4.3:
+          ;; <http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6395191>.
+          ,,@(if (string=? (%current-system) "i686-solaris")
+                 '("--without-cxx-binding")
+                 '()))
+        #:tests? #f                               ; no "check" target
+        #:phases (alist-cons-after
+                  'install 'post-install ,post-install-phase
+                  (alist-cons-before
+                   'configure 'patch-makefile-SHELL
+                   ,patch-makefile-phase
+                   (alist-replace
+                    'configure
+                    ,configure-phase
+                    %standard-phases)))))
      (self-native-input? #t)
      (synopsis
       "GNU Ncurses, a free software emulation of curses in SVR4 and more")
diff --git a/guix/build-system/gnu.scm b/guix/build-system/gnu.scm
index 4f84b3ccee..fa3b3b14b6 100644
--- a/guix/build-system/gnu.scm
+++ b/guix/build-system/gnu.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2012, 2013 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -66,12 +66,8 @@ when GUILE is #f."
     (location (if (pair? loc) (source-properties->location loc) loc))
     (arguments
      (let ((args (package-arguments p)))
-       (if (procedure? args)
-           (lambda (system)
-             `(#:guile ,guile
-               #:implicit-inputs? #f ,@(args system)))
-           `(#:guile ,guile
-             #:implicit-inputs? #f ,@args))))
+       `(#:guile ,guile
+         #:implicit-inputs? #f ,@args)))
     (native-inputs (map rewritten-input
                         (filtered-inputs (package-native-inputs p))))
     (propagated-inputs (map rewritten-input
@@ -95,23 +91,19 @@ configure flags for VARIABLE, the associated value is augmented."
 
     (package (inherit p)
       (arguments
-       (lambda (system)
-         (let ((args (match (package-arguments p)
-                       ((? procedure? proc)
-                        (proc system))
-                       (x x))))
-          (substitute-keyword-arguments args
-            ((#:configure-flags flags)
-             (let* ((var= (string-append variable "="))
-                    (len  (string-length var=)))
-               `(cons ,(string-append var= value)
-                      (map (lambda (flag)
-                             (if (string-prefix? ,var= flag)
-                                 (string-append
-                                  ,(string-append var= value " ")
-                                  (substring flag ,len))
-                                 flag))
-                           ,flags))))))))
+       (let ((args (package-arguments p)))
+         (substitute-keyword-arguments args
+           ((#:configure-flags flags)
+            (let* ((var= (string-append variable "="))
+                   (len  (string-length var=)))
+              `(cons ,(string-append var= value)
+                     (map (lambda (flag)
+                            (if (string-prefix? ,var= flag)
+                                (string-append
+                                 ,(string-append var= value " ")
+                                 (substring flag ,len))
+                                flag))
+                          ,flags)))))))
       (inputs (rewritten-inputs (package-inputs p)))
       (propagated-inputs (rewritten-inputs (package-propagated-inputs p))))))
 
@@ -125,21 +117,14 @@ configure flags for VARIABLE, the associated value is augmented."
     (package (inherit p)
       (location (source-properties->location loc))
       (arguments
-       (let ((augment (lambda (args)
-                        (let ((a (default-keyword-arguments args
-                                   '(#:configure-flags '()
-                                     #:strip-flags #f))))
-                          (substitute-keyword-arguments a
-                            ((#:configure-flags flags)
-                             `(cons* "--disable-shared"
-                                     "LDFLAGS=-static"
-                                     ,flags))
-                            ((#:strip-flags _)
-                             ''("--strip-all")))))))
-         (if (procedure? args)
-             (lambda x
-               (augment (apply args x)))
-             (augment args)))))))
+       (let ((a (default-keyword-arguments args
+                  '(#:configure-flags '()
+                    #:strip-flags #f))))
+         (substitute-keyword-arguments a
+           ((#:configure-flags flags)
+            `(cons* "--disable-shared" "LDFLAGS=-static" ,flags))
+           ((#:strip-flags _)
+            ''("--strip-all"))))))))
 
 
 (define %store
diff --git a/guix/packages.scm b/guix/packages.scm
index a9534adfec..a76e51a5d0 100644
--- a/guix/packages.scm
+++ b/guix/packages.scm
@@ -110,7 +110,7 @@ representation."
   (source package-source)                 ; <origin> instance
   (build-system package-build-system)     ; build system
   (arguments package-arguments            ; arguments for the build method
-             (default '()))
+             (default '()) (thunked))
 
   (inputs package-inputs                  ; input packages or derivations
           (default '()))
@@ -290,24 +290,26 @@ PACKAGE for SYSTEM."
   ;; because some derivations, such as the implicit inputs of the GNU build
   ;; system, will be queried many, many times in a row.
   (cached package system
-          (match package
-            (($ <package> name version source (= build-system-builder builder)
-                args inputs propagated-inputs native-inputs self-native-input?
-                outputs)
-             ;; TODO: For `search-paths', add a builder prologue that calls
-             ;; `set-path-environment-variable'.
-             (let ((inputs (map expand-input
-                                (package-transitive-inputs package))))
-
-               (apply builder
-                      store (package-full-name package)
-                      (and source
-                           (package-source-derivation store source system))
-                      inputs
-                      #:outputs outputs #:system system
-                      (if (procedure? args)
-                          (args system)
-                          args)))))))
+
+          ;; Bind %CURRENT-SYSTEM so that thunked field values can refer
+          ;; to it.
+          (parameterize ((%current-system system))
+            (match package
+              (($ <package> name version source (= build-system-builder builder)
+                  args inputs propagated-inputs native-inputs self-native-input?
+                  outputs)
+               ;; TODO: For `search-paths', add a builder prologue that calls
+               ;; `set-path-environment-variable'.
+               (let ((inputs (map expand-input
+                                  (package-transitive-inputs package))))
+
+                 (apply builder
+                        store (package-full-name package)
+                        (and source
+                             (package-source-derivation store source system))
+                        inputs
+                        #:outputs outputs #:system system
+                        (args))))))))
 
 (define* (package-cross-derivation store package)
   ;; TODO