build: Add 'waf-build-system'.

* guix/build-system/waf.scm,
  guix/build/waf-build-system.scm: New files.
* Makefile.am (MODULES): Add them.
* doc/guix.texi (Build Systems): Document waf-build-system.

Makefile.am

@@ -53,6 +53,7 @@ MODULES =					\
   guix/build-system/gnu.scm			\
   guix/build-system/perl.scm			\
   guix/build-system/python.scm			\
+  guix/build-system/waf.scm			\
   guix/build-system/ruby.scm			\
   guix/build-system/trivial.scm			\
   guix/ftp-client.scm				\
@@ -72,6 +73,7 @@ MODULES =					\
   guix/build/perl-build-system.scm		\
   guix/build/python-build-system.scm		\
   guix/build/ruby-build-system.scm		\
+  guix/build/waf-build-system.scm		\
   guix/build/store-copy.scm			\
   guix/build/utils.scm				\
   guix/build/union.scm				\

doc/guix.texi

@@ -1913,6 +1913,18 @@ Which Ruby package is used can be specified with the @code{#:ruby}
 parameter.
 @end defvr
 
+@defvr {Scheme Variable} waf-build-system
+This variable is exported by @code{(guix build-system waf)}.  It
+implements a build procedure around the @code{waf} script.  The common
+phases---@code{configure}, @code{build}, and @code{install}---are
+implemented by passing their names as arguments to the @code{waf}
+script.
+
+The @code{waf} script is executed by the Python interpreter.  Which
+Python package is used to run the script can be specified with the
+@code{#:python} parameter.
+@end defvr
+
 Lastly, for packages that do not need anything as sophisticated, a
 ``trivial'' build system is provided.  It is trivial in the sense that
 it provides basically no support: it does not pull any implicit inputs,

guix/build-system/waf.scm

@@ -0,0 +1,128 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2015 Ricardo Wurmus <rekado@elephly.net>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix build-system waf)
+  #:use-module (guix store)
+  #:use-module (guix utils)
+  #:use-module (guix packages)
+  #:use-module (guix derivations)
+  #:use-module (guix build-system)
+  #:use-module (guix build-system gnu)
+  #:use-module ((guix build-system python)
+                #:select (default-python default-python2))
+  #:use-module (ice-9 match)
+  #:use-module (srfi srfi-26)
+  #:export (waf-build
+            waf-build-system))
+
+;; Commentary:
+;;
+;; Standard build procedure for applications using 'waf'.  This is very
+;; similar to the 'python-build-system' and is implemented as an extension of
+;; 'gnu-build-system'.
+;;
+;; Code:
+
+(define* (lower name
+                #:key source inputs native-inputs outputs system target
+                (python (default-python))
+                #:allow-other-keys
+                #:rest arguments)
+  "Return a bag for NAME."
+  (define private-keywords
+    '(#:source #:target #:python #:inputs #:native-inputs))
+
+  (and (not target)                               ;XXX: no cross-compilation
+       (bag
+         (name name)
+         (system system)
+         (host-inputs `(,@(if source
+                              `(("source" ,source))
+                              '())
+                        ,@inputs
+
+                        ;; Keep the standard inputs of 'gnu-build-system'.
+                        ,@(standard-packages)))
+         (build-inputs `(("python" ,python)
+                         ,@native-inputs))
+         (outputs outputs)
+         (build waf-build) ; only change compared to 'lower' in python.scm
+         (arguments (strip-keyword-arguments private-keywords arguments)))))
+
+(define* (waf-build store name inputs
+                       #:key
+                       (tests? #t)
+                       (test-target "check")
+                       (configure-flags ''())
+                       (phases '(@ (guix build waf-build-system)
+                                   %standard-phases))
+                       (outputs '("out"))
+                       (search-paths '())
+                       (system (%current-system))
+                       (guile #f)
+                       (imported-modules '((guix build waf-build-system)
+                                           (guix build gnu-build-system)
+                                           (guix build utils)))
+                       (modules '((guix build waf-build-system)
+                                  (guix build utils))))
+  "Build SOURCE with INPUTS.  This assumes that SOURCE provides a 'waf' file
+as its build system."
+  (define builder
+    `(begin
+       (use-modules ,@modules)
+       (waf-build #:name ,name
+                  #:source ,(match (assoc-ref inputs "source")
+                              (((? derivation? source))
+                               (derivation->output-path source))
+                              ((source)
+                               source)
+                              (source
+                               source))
+                  #:configure-flags ,configure-flags
+                  #:system ,system
+                  #:test-target ,test-target
+                  #:tests? ,tests?
+                  #:phases ,phases
+                  #:outputs %outputs
+                  #:search-paths ',(map search-path-specification->sexp
+                                        search-paths)
+                  #:inputs %build-inputs)))
+
+  (define guile-for-build
+    (match guile
+      ((? package?)
+       (package-derivation store guile system #:graft? #f))
+      (#f                                         ; the default
+       (let* ((distro (resolve-interface '(gnu packages commencement)))
+              (guile  (module-ref distro 'guile-final)))
+         (package-derivation store guile system #:graft? #f)))))
+
+  (build-expression->derivation store name builder
+                                #:inputs inputs
+                                #:system system
+                                #:modules imported-modules
+                                #:outputs outputs
+                                #:guile-for-build guile-for-build))
+
+(define waf-build-system
+  (build-system
+    (name 'waf)
+    (description "The standard waf build system")
+    (lower lower)))
+
+;;; waf.scm ends here

guix/build/waf-build-system.scm

@@ -0,0 +1,86 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2015 Ricardo Wurmus <rekado@elephly.net>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix build waf-build-system)
+  #:use-module ((guix build gnu-build-system) #:prefix gnu:)
+  #:use-module (guix build utils)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 ftw)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
+  #:export (%standard-phases
+            waf-build))
+
+;; Commentary:
+;;
+;; Builder-side code of the standard waf build procedure.
+;;
+;; Code:
+
+
+(define (call-waf command params)
+  (if (file-exists? "waf")
+      (begin
+         (format #t "running \"python waf\" with command ~s and parameters ~s~%"
+                command params)
+         (zero? (apply system* "python" "waf" command params)))
+      (error "no waf found")))
+
+(define* (configure #:key target native-inputs inputs outputs
+                    (configure-flags '())
+                    #:allow-other-keys)
+  "Build a given waf application."
+  (let* ((prefix (assoc-ref outputs "out"))
+         (flags  `(,(string-append "--prefix=" prefix)
+                   ,@configure-flags)))
+    (call-waf "configure" flags)))
+
+(define* (build #:rest empty)
+  "Build a given waf application."
+  (call-waf "build" '()))
+
+(define* (check #:key tests? test-target #:allow-other-keys)
+  "Run the test suite of a given waf application."
+  (if tests?
+    (call-waf test-target '())
+    #t))
+
+(define* (install #:key outputs inputs (configure-flags '())
+                  #:allow-other-keys)
+  "Install a given waf application."
+  (let* ((out (assoc-ref outputs "out"))
+         (params (append (list (string-append "--prefix=" out))
+                         configure-flags)))
+        (call-waf "install" params)))
+
+(define %standard-phases
+  (alist-replace
+   'configure configure
+   (alist-replace
+    'build build
+    (alist-replace
+     'check check
+     (alist-replace 'install install
+                    gnu:%standard-phases)))))
+
+(define* (waf-build #:key inputs (phases %standard-phases)
+                       #:allow-other-keys #:rest args)
+  "Build the given waf application, applying all of PHASES in order."
+  (apply gnu:gnu-build #:inputs inputs #:phases phases args))
+
+;;; waf-build-system.scm ends here