lib/prelude/monad.rb in prelude-0.0.2 vs lib/prelude/monad.rb in prelude-0.0.3

@@ -21,31 +21,108 @@
 #     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 #++
 
 module Prelude
 
-  # $Id: monad.rb 7 2006-09-06 17:03:26Z prelude $
+  # $Id: monad.rb 13 2006-09-11 05:19:16Z prelude $
   #
-  # The Monad is an Array only in an implementation sence of the word
-  class Monad < Array
+  module Monad
+    State = {}
 
-    def wrap(v)
-      [v]
+    def wrap
+      State[object_id] = self
+      self
     end
 
+    def unwrap
+      State[object_id]
+    end
+
     def empty
-      []
+      State[object_id] = nil
+      self
     end
     
-    def join
+    def Monad.join(arr)
       r = []
-      each {|a| r.push *a}
+      arr.each {|a| r.push *a}
       r
     end
 
-    def bind(&block)
-      map(&block).join
-    end
+    def bind(f=nil)
+      case
+      when f.kind_of?(Symbol) || f.kind_of?(Method) || f.kind_of?(Proc) :
+          State[object_id] = f.to_proc.call(State[object_id])
+        self
+        
+#      when f.kind_of?(Proc) :
+#          State[object_id] = f.call(State[object_id])
+#        self
 
+      else
+        f
+      end # case
+    end # bind
+
+    alias << bind
+
   end # Monad
+
+#   class Maybe < Monad
+    
+#     # maybe		-- :: b -> (a -> b) -> Maybe a -> b
+#     def maybe
+#       warn "Method 'maybe' is not implemented yet." if $VERBOSE
+#       return []
+#     end
+
+#     # isJust		-- :: Maybe a -> Bool
+#     def isJust
+#       warn "Method 'isJust' is not implemented yet." if $VERBOSE
+#       return []
+#     end
+
+#     # isNothing		-- :: Maybe a -> Bool
+#     def isNothing
+#       warn "Method 'isNothing' is not implemented yet." if $VERBOSE
+#       return []
+#     end
+
+#     # fromJust		-- :: Maybe a -> a
+#     def fromJust
+#       warn "Method 'fromJust' is not implemented yet." if $VERBOSE
+#       return []
+#     end
+
+#     # fromMaybe		-- :: a -> Maybe a -> a
+#     def fromMaybe
+#       warn "Method 'fromMaybe' is not implemented yet." if $VERBOSE
+#       return []
+#     end
+
+#     # listToMaybe       -- :: [a] -> Maybe a
+#     def listToMaybe
+#       warn "Method 'listToMaybe' is not implemented yet." if $VERBOSE
+#       return []
+#     end
+
+#     # maybeToList	-- :: Maybe a -> [a]
+#     def maybeToList
+#       warn "Method 'maybeToList' is not implemented yet." if $VERBOSE
+#       return []
+#     end
+
+#     # catMaybes		-- :: [Maybe a] -> [a]
+#     def catMaybes
+#       warn "Method 'catMaybes' is not implemented yet." if $VERBOSE
+#       return []
+#     end
+
+#     # mapMaybe		-- :: (a -> Maybe b) -> [a] -> [b]
+#     def mapMaybe
+#       warn "Method 'mapMaybe' is not implemented yet." if $VERBOSE
+#       return []
+#     end
+
+#   end # Maybe
 
 end # Prelude