lib/haskell.rb in haskell-0.0.1 vs lib/haskell.rb in haskell-0.0.2

@@ -1,6 +1,44 @@
-require "haskell/version"
-require "haskell/haskell"
+require 'haskell/type_list'
 
 module Haskell
-  # Your code goes here...
+  class << self
+    def assert_arg_type(meth, args, klasses)
+
+      args.each_with_index do |arg, i|
+        if wrong_type?(arg, klasses[i])
+          raise ArgumentError, "Wrong type of argument, type of #{arg.inspect} should be #{klasses[i]}"
+        end
+      end
+    end
+
+    def assert_rtn_type(meth, rtn, klass)
+      if wrong_type?(rtn, klass)
+        raise TypeError, "Expected #{meth} to return #{klass} but got #{rtn.inspect} instead"
+      end
+    end
+
+    def wrong_type?(obj, klass)
+      !(obj.is_a?(klass) || klass == Any)
+    end
+  end
 end
+
+class Module
+  private
+    def __haskell__
+      prepend (@__haskell__ = Module.new) unless @__haskell__
+      @__haskell__
+    end
+
+    def type(type_list, meth)
+      __haskell__.send(:define_method, meth) do |*args, &block|
+        ::Haskell.assert_arg_type(meth, args, type_list.args)
+        rtn = super(*args, &block)
+        ::Haskell.assert_rtn_type(meth, rtn, type_list.rtn)
+        rtn
+      end
+      self
+    end
+end
+
+class Any; end