Refactor Homebrew formula using Makefile

See details in this blog post: https://nshipster.com/homebrew/

Formula/beak.rb

@@ -1,21 +1,15 @@
 class Beak < Formula
-  desc "A command line interface for your Swift scripts"
+  desc "Command-line interface for your Swift scripts"
   homepage "https://github.com/yonaskolb/Beak"
-  url "https://github.com/yonaskolb/Beak/archive/0.4.0.tar.gz"
-  sha256 "c306292c94aadd648437a2334936231baaa9ba195738aeeb28379fcb34900d41"
-  head "https://github.com/yonaskolb/Beak.git"
+  url "https://github.com/yonaskolb/Beak.git", :tag => "0.4.0", :revision => "8508e02da82c279b3cf1719bd226dc8c94538a71"
 
-  depends_on :xcode
+  depends_on :xcode => ["10.0", :build]
 
   def install
-
-    # fixes an issue an issue in homebrew when both Xcode 9.3+ and command line tools are installed
-    # see more details here https://github.com/Homebrew/brew/pull/4147
-    ENV["CC"] = Utils.popen_read("xcrun -find clang").chomp
+    system "make", "install", "prefix=#{prefix}"
+  end
 
-    build_path = "#{buildpath}/.build/release/beak"
-    ohai "Building Beak"
-    system("swift build --disable-sandbox -c release -Xswiftc -static-stdlib")
-    bin.install build_path
+  test do
+    system bin/"beak", "version"
   end
 end

Makefile

@@ -0,0 +1,38 @@
+SHELL = /bin/bash
+
+prefix ?= /usr/local
+bindir ?= $(prefix)/bin
+libdir ?= $(prefix)/lib
+srcdir = Sources
+
+REPODIR = $(shell pwd)
+BUILDDIR = $(REPODIR)/.build
+SOURCES = $(wildcard $(srcdir)/**/*.swift)
+
+.DEFAULT_GOAL = all
+
+.PHONY: all
+all: beak
+
+beak: $(SOURCES)
+	@swift build \
+		-c release \
+		--disable-sandbox \
+		--build-path "$(BUILDDIR)"
+
+.PHONY: install
+install: beak
+	@install -d "$(bindir)" "$(libdir)"
+	@install "$(BUILDDIR)/release/beak" "$(bindir)"
+
+.PHONY: uninstall
+uninstall:
+	@rm -rf "$(bindir)/beak"
+
+.PHONY: clean
+distclean:
+	@rm -f $(BUILDDIR)/release
+
+.PHONY: clean
+clean: distclean
+	@rm -rf $(BUILDDIR)