Augment `build-expression->derivation' with #:modules; add `http-fetch'.

* guix/derivations.scm (imported-modules): New procedure.
  (build-expression->derivation): New keyword argument `modules'.
  Use `imported-modules' when MODULES is non-empty, and pass it with
  `-L' to GUILE.

* guix/build/http.scm, guix/http.scm, tests/builders.scm: New files.

1 files changed, 42 insertions, 0 deletions

diff --git a/guix/build/http.scm b/guix/build/http.scm
new file mode 100644
index 0000000000..f6f797f9cf
--- /dev/null
+++ b/guix/build/http.scm
@@ -0,0 +1,42 @@
+;;; Guix --- Nix package management from Guile.         -*- coding: utf-8 -*-
+;;; Copyright (C) 2012 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; This file is part of Guix.
+;;;
+;;; 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.
+;;;
+;;; 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 Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix build http)
+  #:use-module (web client)
+  #:use-module (web uri)
+  #:use-module (rnrs io ports)
+  #:use-module (srfi srfi-11)
+  #:export (http-fetch))
+
+;;; Commentary:
+;;;
+;;; Fetch data such as tarballs over HTTP (builder-side code).
+;;;
+;;; Code:
+
+(define (http-fetch url file)
+  "Fetch data from URL and write it to FILE.  Return FILE on success."
+
+  ;; FIXME: Use a variant of `http-get' that returns a port instead of
+  ;; loading everything in memory.
+  (let-values (((resp bv)
+                (http-get (string->uri url) #:decode-body? #f)))
+    (call-with-output-file file
+      (lambda (p)
+        (put-bytevector p bv))))
+  file)