gnu: Add es.

* gnu/packages/shells.scm (es): New variable.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/shells.scm

@@ -6,6 +6,7 @@
 ;;; Copyright © 2016 Tobias Geerinckx-Rice <me@tobias.gr>
 ;;; Copyright © 2016 Stefan Reichör <stefan@xsteve.at>
 ;;; Copyright © 2017 Ricardo Wurmus <rekado@elephly.net>
+;;; Copyright © 2017 ng0 <contact.ng0@cryptolab.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -27,6 +28,7 @@
   #:use-module (gnu packages algebra)
   #:use-module (gnu packages autotools)
   #:use-module (gnu packages base)
+  #:use-module (gnu packages bison)
   #:use-module (gnu packages documentation)
   #:use-module (gnu packages libedit)
   #:use-module (gnu packages ncurses)
@@ -176,6 +178,42 @@ has a small feature set similar to a traditional Bourne shell.")
     (home-page "http://github.com/rakitzis/rc")
     (license zlib)))
 
+(define-public es
+  (package
+    (name "es")
+    (version "0.9.1")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (string-append "https://github.com/wryun/es-shell/releases/"
+                           "download/v" version "/es-" version ".tar.gz"))
+       (sha256
+        (base32
+         "1fplzxc6lncz2lv2fyr2ig23rgg5j96rm2bbl1rs28mik771zd5h"))
+       (file-name (string-append name "-" version ".tar.gz"))))
+    (build-system gnu-build-system)
+    (arguments
+     `(#:test-target "test"
+       #:phases
+       (modify-phases %standard-phases
+         (add-before 'configure 're-enter-rootdir
+           ;; The tarball has no folder.
+           (lambda _
+             (chdir ".."))))))
+    (inputs
+     `(("readline" ,readline)))
+    (native-inputs
+     `(("bison" ,bison)))
+    (synopsis "Extensible shell with higher-order functions")
+    (description
+     "Es is an extensible shell.  The language was derived from the Plan 9
+shell, rc, and was influenced by functional programming languages, such as
+Scheme, and the Tcl embeddable programming language.  This implementation is
+derived from Byron Rakitzis's public domain implementation of rc, and was
+written by Paul Haahr and Byron Rakitzis.")
+    (home-page "https://wryun.github.io/es-shell/")
+    (license public-domain)))
+
 (define-public tcsh
   (package
     (name "tcsh")