[project @ 2003-08-22 08:58:30 by panne]

[ghc-base.git] / GHC / Base.lhs

diff --git a/GHC/Base.lhs b/GHC/Base.lhs
index 9cdd755..76ade71 100644 (file)
--- a/GHC/Base.lhs
+++ b/GHC/Base.lhs
@@ -196,9 +196,34 @@ class  (Eq a) => Ord a  where
 %*********************************************************
 
 \begin{code}
+{- | The 'Functor' class is used for types that can be mapped over.
+Instances of 'Functor' should satisfy the following laws:
+
+> fmap id  ==  id
+> fmap (f . g)  ==  fmap f . fmap g
+
+The instances of 'Functor' for lists, 'Maybe' and 'IO' defined in the "Prelude"
+satisfy these laws.
+-}
+
 class  Functor f  where
     fmap        :: (a -> b) -> f a -> f b
 
+{- | The 'Monad' class defines the basic operations over a /monad/.
+Instances of 'Monad' should satisfy the following laws:
+
+> return a >>= k  ==  k a
+> m >>= return  ==  m
+> m >>= (\x -> k x >>= h)  ==  (m >>= k) >>= h
+
+Instances of both 'Monad' and 'Functor' should additionally satisfy the law:
+
+> fmap f xs  ==  xs >>= return . f
+
+The instances of 'Monad' for lists, 'Maybe' and 'IO' defined in the "Prelude"
+satisfy these laws.
+-}
+
 class  Monad m  where
     (>>=)       :: m a -> (a -> m b) -> m b
     (>>)        :: m a -> m b -> m b
@@ -399,10 +424,10 @@ not                       :: Bool -> Bool
 not True               =  False
 not False              =  True
 
--- |'otherwise' is defined as the value 'True'; it helps to make
+-- |'otherwise' is defined as the value 'True'.  It helps to make
 -- guards more readable.  eg.
 --
--- >  f x | x \< 0     = ...
+-- >  f x | x < 0     = ...
 -- >      | otherwise = ...
 otherwise              :: Bool
 otherwise              =  True
@@ -687,6 +712,7 @@ in the case when the argument is already known to be evaluated.
 
 \begin{code}
 {-# INLINE getTag #-}
+getTag :: a -> Int#
 getTag x = x `seq` dataToTag# x
 \end{code}