Remove haskell-platform

The latest version haskell-platform features an entirely different
build system that does not play well with Homebrew, so it is being
removed in favor of the ghc and cabal-install formulae.

The binary installer can also be used instead:
  https://www.haskell.org/platform/mac.html

Closes Homebrew/homebrew#31609.

Formula/cabal-install.rb

@@ -15,8 +15,6 @@ class CabalInstall < Formula
 
   depends_on "ghc"
 
-  conflicts_with "haskell-platform"
-
   fails_with :clang if MacOS.version < :mavericks # Same as ghc.rb
 
   def install

Formula/ghc.rb

@@ -135,12 +135,6 @@ class Ghc < Formula
     end
   end
 
-  def caveats; <<-EOS.undent
-    This brew is for GHC only; you might also be interested in cabal-install
-    or haskell-platform.
-    EOS
-  end
-
   test do
     hello = (testpath/"hello.hs")
     hello.write('main = putStrLn "Hello Homebrew"')

Formula/haskell-platform.rb

@@ -1,40 +0,0 @@
-require "formula"
-
-class HaskellPlatform < Formula
-  homepage "http://hackage.haskell.org/platform/"
-  url "http://lambda.haskell.org/platform/download/2013.2.0.0/haskell-platform-2013.2.0.0.tar.gz"
-  sha1 "8669bb5add1826c0523fb130c095fb8bf23a30ce"
-  bottle do
-    sha1 "87ee98c01e11b63903074285749c284ae50f1b6a" => :mavericks
-    sha1 "03b7b5b66c02af03fac4ce5e8d305377997d19da" => :mountain_lion
-    sha1 "95d3a37c87a96ba0703dd4f9065661583fa9b902" => :lion
-  end
-
-  revision 1
-
-  depends_on "ghc"
-
-  conflicts_with "cabal-install"
-
-  def install
-    # libdir doesn't work if passed to configure, needs to be set in the environment
-    system "./configure", "--prefix=#{prefix}"
-    ENV["EXTRA_CONFIGURE_OPTS"] = "--libdir=#{lib}/ghc"
-    system "make install"
-  end
-
-  def caveats; <<-EOS.undent
-    Add cabal binaries to your PATH:
-      export PATH=~/.cabal/bin:$PATH
-
-    Run `cabal update` to initialize the package list.
-
-    If you are replacing a previous version of haskell-platform, you may want
-    to unregister packages belonging to the old version. You can find broken
-    packages using:
-      ghc-pkg check --simple-output
-    You can uninstall them using:
-      ghc-pkg check --simple-output | xargs -n 1 ghc-pkg unregister --force
-    EOS
-  end
-end