gnu: Add js-mathjax.

* gnu/packages/javascript.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* gnu/packages/javascript.scm (js-mathjax): New variable.

gnu/local.mk

@@ -208,6 +208,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/packages/irc.scm  			\
   %D%/packages/iso-codes.scm			\
   %D%/packages/java.scm				\
+  %D%/packages/javascript.scm			\
   %D%/packages/jemalloc.scm			\
   %D%/packages/jrnl.scm				\
   %D%/packages/julia.scm			\

gnu/packages/javascript.scm

@@ -0,0 +1,85 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2017 Arun Isaac <arunisaac@systemreboot.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 (gnu packages javascript)
+  #:use-module ((guix licenses) #:prefix license:)
+  #:use-module (gnu packages)
+  #:use-module (gnu packages base)
+  #:use-module (gnu packages compression)
+  #:use-module (gnu packages fonts)
+  #:use-module (gnu packages lisp)
+  #:use-module (guix packages)
+  #:use-module (guix download)
+  #:use-module (guix build-system trivial))
+
+(define-public js-mathjax
+  (package
+    (inherit font-mathjax)
+    (name "js-mathjax")
+    (arguments
+     `(#:modules ((guix build utils))
+       #:builder
+       (begin
+         (use-modules (guix build utils)
+                      (ice-9 match)
+                      (ice-9 popen)
+                      (ice-9 regex))
+         (set-path-environment-variable
+          "PATH" '("bin") (map (match-lambda
+                                 ((_ . input)
+                                  input))
+                               %build-inputs))
+         (set-path-environment-variable
+          "GUIX_LOCPATH" '("lib/locale")
+          (list (assoc-ref %build-inputs "glibc-utf8-locales")))
+         (setenv "LANG" "en_US.UTF-8")
+         (let ((install-directory (string-append %output "/share/javascript/mathjax")))
+           (system* "tar" "xvf" (assoc-ref %build-inputs "source")
+                    "MathJax-2.7.1/unpacked" "--strip" "2")
+           (mkdir-p install-directory)
+           (symlink (string-append (assoc-ref %build-inputs "font-mathjax")
+                                   "/share/fonts/mathjax")
+                    (string-append install-directory "/fonts"))
+
+           (for-each
+            (lambda (file)
+              (let ((installed (string-append install-directory
+                                              ;; remove prefix "."
+                                              (string-drop file 1))))
+                (format #t "~a -> ~a~%" file installed)
+                (cond
+                 ((string-match "\\.js$" file)
+                  (mkdir-p (dirname installed))
+                  (let ((minified (open-pipe* OPEN_READ "uglify-js" file)))
+                    (call-with-output-file installed
+                      (lambda (port)
+                        (dump-port minified port)))))
+                 (else
+                  (install-file file (dirname installed))))))
+            (find-files "."))))))
+    (native-inputs
+     `(("font-mathjax" ,font-mathjax)
+       ("glibc-utf8-locales" ,glibc-utf8-locales)
+       ("uglify-js" ,uglify-js)
+       ,@(package-native-inputs font-mathjax)))
+    (synopsis "JavaScript display engine for LaTeX, MathML, and AsciiMath")
+    (description "MathJax is a JavaScript display engine for LaTeX, MathML,
+and AsciiMath notation that works in all modern browsers.  It requires no
+plugins or software to be installed on the browser.  So the page author can
+write web documents that include mathematics and be confident that readers will
+be able to view it naturally and easily.")))