[bug#33431] [PATCH] gnu: Add yarn

[Andrea Frigido <andrea@frisoft.it>]

Hello,

This patch adds yarn as a Guix package.
This is my first patch so I hope this is the correct way of doing it.
Inspired by the nix package:
https://github.com/NixOS/nixpkgs/blob/b37872d4268164614e3ecef6e1f730d48cf5a90f/pkgs/development/tools/yarn/default.nix#L23

Andrea Frigido

---
 gnu/packages/yarn.scm | 75 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 gnu/packages/yarn.scm

diff --git a/gnu/packages/yarn.scm b/gnu/packages/yarn.scm
new file mode 100644
index 000000000..e48313f7f
--- /dev/null
+++ b/gnu/packages/yarn.scm
@@ -0,0 +1,75 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2018 Andrea Frigido <andrea@frisoft.it>
+;;;
+;;; 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 yarn)
+  #:use-module (guix packages)
+  #:use-module (guix download)
+  #:use-module (guix build-system gnu)
+  #:use-module ((guix licenses) #:prefix license:)
+  #:use-module (guix utils)
+  #:use-module (gnu packages node))
+
+(define-public yarn
+  (package
+    (name "yarn")
+    (version "1.12.3")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (string-append
+             "https://github.com/yarnpkg/yarn/releases/download/v"
+             version
+             "/yarn-v"
+             version
+             ".tar.gz"))
+       (sha256
+        (base32
+         "1wi47awrcy5kki9qmmia4h3rpsf5k7yvnpmwsbdlnb62krc4pk82"))))
+    (build-system gnu-build-system)
+    (arguments
+     `(#:phases
+       (modify-phases %standard-phases
+         (delete 'configure)
+         (delete 'check)
+         (delete 'build)
+         (replace 'install
+           (lambda* (#:key outputs #:allow-other-keys)
+             (let* ((out               (assoc-ref %outputs "out"))
+                    (bin               (string-append out "/bin"))
+                    (libexec-yarn      (string-append out "/libexec/yarn"))
+                    (yarn-js           (string-append libexec-yarn
"/bin/yarn.js")))
+               (mkdir-p bin)
+               (mkdir-p libexec-yarn)
+               (copy-recursively "./" libexec-yarn)
+               (symlink yarn-js (string-append bin "/yarn"))
+               (symlink yarn-js (string-append bin "/yarnpkg"))))))))
+
+    (inputs `(("node" ,node)))
+    (synopsis "Fast, reliable, and secure dependency management")
+    (description
+     "Yarn is a fast, reliable, and secure dependency management.  Fast: Yarn
+caches every package it has downloaded, so it never needs to download the
+same package again.  It also does almost everything concurrently to maximize
+resource utilization.  This means even faster installs.  Reliable: Using a
+detailed but concise lockfile format and a deterministic algorithm for install
+operations, Yarn is able to guarantee that any installation that works on one
+system will work exactly the same on another system.
+Secure: Yarn uses checksums to verify the integrity of every installed package
+before its code is executed.")
+    (license license:bsd-2)
+    (home-page "https://yarnpkg.com")))
-- 
2.17.1