Refs: #3507_1726@6h Code Review

1 files changed, 37 insertions, 0 deletions

diff --git a/lib/result.rb b/lib/result.rb
new file mode 100644
index 000000000..96e03d323
--- /dev/null
+++ b/lib/result.rb
@@ -0,0 +1,37 @@
+# A value wrapper adding status information to any value
+# Status can be :ok or :error, we are thusly implementing
+# what is expressed in Elixir/Erlang as result tuples and
+# in Haskell as `Data.Either`
+class Result
+
+  attr_reader :status, :value
+  
+  class << self
+    def ok value
+      make :ok, value
+    end
+    def error value
+      make :error, value
+    end
+
+    def new *args
+      raise NoMethodError, "No default constructor for #{self}"
+    end
+
+    private
+    def make status, value
+      allocate.tap do | o |
+        o.instance_exec do
+          @status = status
+          @value  = value
+        end
+      end
+    end
+  end
+
+  def ok?; status == :ok end
+
+  def == other
+    other.kind_of?(self.class) && other.status == status && other.value == value
+  end
+end