Merge pull request #1899 from uberhacker/add-cabal-package

Add cabal package

packages/cabal.rb

+require 'package'
+
+class Cabal < Package
+  description 'Common Architecture for Building Applications and Libraries'
+  homepage 'https://www.haskell.org/cabal/'
+  version '2.0.0.1'
+  case ARCH
+  when 'i686'
+    source_url 'https://www.haskell.org/cabal/release/cabal-install-2.0.0.1/cabal-install-2.0.0.1-i386-unknown-linux.tar.gz'
+    source_sha256 '3198c04aeddc38847e4b25ad4590f17a9e5e41eba0b6f1c6fba997d7e73388d8'
+  when 'x86_64'
+    source_url 'https://www.haskell.org/cabal/release/cabal-install-2.0.0.1/cabal-install-2.0.0.1-x86_64-unknown-linux.tar.gz'
+    source_sha256 '915f9bc9944a6854ed9255c2a38cb18366fa94e5c7f584ebf139e829bda98764'
+  else
+    puts "#{ARCH} architecture not supported.".lightred
+  end
+
+  depends_on 'ghc'
+
+  def self.install
+    system "install -Dm755 cabal #{CREW_DEST_PREFIX}/bin/cabal"
+  end
+end