Add a new html-utils module

To store code used for rendering HTML across multiple controllers.

Makefile.am

@@ -93,6 +93,7 @@ SOURCES =							\
   guix-data-service/model/package-metadata.scm			\
   guix-data-service/model/package.scm				\
   guix-data-service/model/utils.scm				\
+  guix-data-service/web/html-utils.scm				\
   guix-data-service/web/compare/controller.scm			\
   guix-data-service/web/compare/html.scm			\
   guix-data-service/web/controller.scm				\

guix-data-service/web/html-utils.scm

@@ -0,0 +1,35 @@
+;;; Guix Data Service -- Information about Guix over time
+;;; Copyright © 2019 Christopher Baines <mail@cbaines.net>
+;;;
+;;; This program is free software: you can redistribute it and/or
+;;; modify it under the terms of the GNU Affero General Public License
+;;; as published by the Free Software Foundation, either version 3 of
+;;; the License, or (at your option) any later version.
+;;;
+;;; This program 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
+;;; Affero General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU Affero General Public
+;;; License along with this program.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+(define-module (guix-data-service web html-utils)
+  #:use-module (ice-9 match)
+  #:export (sexp-div))
+
+(define (sexp-div sexp)
+  (match sexp
+    (#(val rest ...)
+     `(div (@ (style "margin-left: 1em;"))
+           "( "
+           ,val
+           " "
+           ,@(map sexp-div rest)
+           " )"))
+    ((("base16" . hash))
+     `(span (@ (style "font-family: monospace;"))
+            ,hash))
+    ((and string val)
+     val)))