Add post module.

* haunt/post.scm: New file.
* Makefile.am (SOURCES): Add it.

haunt/post.scm

@@ -0,0 +1,43 @@
+;;; Haunt --- Static site generator for GNU Guile
+;;; Copyright © 2015 David Thompson <davet@gnu.org>
+;;;
+;;; This file is part of Haunt.
+;;;
+;;; Haunt 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.
+;;;
+;;; Haunt 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 Haunt.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+;;
+;; Post data type.
+;;
+;;; Code:
+
+(define-module (haunt post)
+  #:use-module (srfi srfi-9)
+  #:export (make-post
+            post?
+            post-file-name
+            post-sxml
+            post-metadata
+            post-ref))
+
+(define-record-type <post>
+  (make-post file-name metadata sxml)
+  post?
+  (file-name post-file-name)
+  (metadata post-metadata)
+  (sxml post-sxml))
+
+(define (post-ref post key)
+  "Return the metadata corresponding to KEY within POST."
+  (assq-ref (post-metadata post) key))