-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Handle Boolean values generatically.
--   
--   This package provides various functions and classes for dealing with
--   things which are like Boolean values. It also defines a few useful
--   instances. The main benefit is the ability to use the usual
--   <tt>&amp;&amp;</tt>, etc. operators without having to invent new
--   operator names for every kind of Bool-like thing.
@package AC-Boolean
@version 1.0.0


-- | Type classes (and instances) for things that are like Booleans.
--   
--   The names of methods in <a>Boolean</a> clash with the standard
--   Prelude, so you probably want to inport the Prelude hiding these three
--   names (since the class methods do the same thing, but with more
--   general type signatures).
--   
--   An interesting consequence of the <a>Boolean</a> instance for monads
--   is that <a>Maybe</a> <a>Bool</a> is a <a>Boolean</a>. You can use this
--   to implement 3-value logic ("true", "false" and "other"), with
--   <a>Nothing</a> implementing "other". Any logical operations yield
--   <a>Nothing</a> unless all arguments are <a>Just</a> something. (This
--   is usually the behaviour you want.)
module Data.Boolean

-- | Typeclass for things that have true and false values.
--   
--   Instances:
--   
--   <ul>
--   <li>Normal <a>Bool</a> values (obviously).</li>
--   <li>Any function that yields a <a>BoolValue</a> as its result. (For
--   example, <a>true</a> is just a constant function that always returns a
--   truth value, regardless of its input.)</li>
--   <li>Any monadic action that yields a <a>BoolValue</a> as its result.
--   (This is just <a>return</a> applied to the appropriate
--   <a>BoolValue</a>.)</li>
--   </ul>
class BoolValue b
true :: (BoolValue b) => b
false :: (BoolValue b) => b

-- | Convert a <a>Bool</a> value to the appropriate <a>BoolValue</a>.
lift_bool :: (BoolValue b) => Bool -> b

-- | Typeclass for things that support Boolean operators.
--   
--   Instances:
--   
--   <ul>
--   <li>Normal <a>Bool</a> values (obviously).</li>
--   <li>Any function that returns a <a>Boolean</a>. (The result is a new
--   function that runs the old function(s) and applies the appropriate
--   operator to the result(s).)</li>
--   <li>Any monadic action that returns a <a>Boolean</a>. (Again, the
--   result is a new action that runs the existing action(s) and applies
--   the appropriate operator to the result(s).)</li>
--   </ul>
class Boolean b
(&&) :: (Boolean b) => b -> b -> b
(||) :: (Boolean b) => b -> b -> b
not :: (Boolean b) => b -> b
xor :: (Boolean b) => b -> b -> b
instance (Monad m, Boolean b) => Boolean (m b)
instance (Boolean b) => Boolean (x -> b)
instance Boolean Bool
instance (Monad m, BoolValue b) => BoolValue (m b)
instance (BoolValue b) => BoolValue (x -> b)
instance BoolValue Bool