Add tests from testsuite/tests/h98

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

diff --git a/GHC/List.lhs b/GHC/List.lhs
index 5dcf7e0..ff8593c 100644 (file)
--- a/GHC/List.lhs
+++ b/GHC/List.lhs
@@ -1,6 +1,7 @@
 \begin{code}
-{-# OPTIONS_GHC -XNoImplicitPrelude #-}
+{-# LANGUAGE CPP, NoImplicitPrelude, MagicHash #-}
 {-# OPTIONS_HADDOCK hide #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  GHC.List
@@ -108,7 +109,7 @@ null                    :: [a] -> Bool
 null []                 =  True
 null (_:_)              =  False
 
--- | 'length' returns the length of a finite list as an 'Int'.
+-- | /O(n)/. 'length' returns the length of a finite list as an 'Int'.
 -- It is an instance of the more general 'Data.List.genericLength',
 -- the result type of which may be any kind of number.
 length                  :: [a] -> Int
@@ -503,11 +504,15 @@ or (x:xs)       =  x || or xs
 #endif
 
 -- | Applied to a predicate and a list, 'any' determines if any element
--- of the list satisfies the predicate.
+-- of the list satisfies the predicate.  For the result to be
+-- 'False', the list must be finite; 'True', however, results from a 'True'
+-- value for the predicate applied to an element at a finite index of a finite or infinite list.
 any                     :: (a -> Bool) -> [a] -> Bool
 
 -- | Applied to a predicate and a list, 'all' determines if all elements
--- of the list satisfy the predicate.
+-- of the list satisfy the predicate. For the result to be
+-- 'True', the list must be finite; 'False', however, results from a 'False'
+-- value for the predicate applied to an element at a finite index of a finite or infinite list.
 all                     :: (a -> Bool) -> [a] -> Bool
 #ifdef USE_REPORT_PRELUDE
 any p                   =  or . map p
@@ -527,7 +532,8 @@ all p (x:xs)    =  p x && all p xs
 #endif
 
 -- | 'elem' is the list membership predicate, usually written in infix form,
--- e.g., @x \`elem\` xs@.
+-- e.g., @x \`elem\` xs@.  For the result to be
+-- 'False', the list must be finite; 'True', however, results from an element equal to @x@ found at a finite index of a finite or infinite list.
 elem                    :: (Eq a) => a -> [a] -> Bool
 
 -- | 'notElem' is the negation of 'elem'.
@@ -647,7 +653,7 @@ zip _      _      = []
 
 {-# INLINE [0] zipFB #-}
 zipFB :: ((a, b) -> c -> d) -> a -> b -> c -> d
-zipFB c x y r = (x,y) `c` r
+zipFB c = \x y r -> (x,y) `c` r
 
 {-# RULES
 "zip"      [~1] forall xs ys. zip xs ys = build (\c n -> foldr2 (zipFB c) n xs ys)
@@ -680,9 +686,11 @@ zipWith :: (a->b->c) -> [a]->[b]->[c]
 zipWith f (a:as) (b:bs) = f a b : zipWith f as bs
 zipWith _ _      _      = []
 
+-- zipWithFB must have arity 2 since it gets two arguments in the "zipWith"
+-- rule; it might not get inlined otherwise
 {-# INLINE [0] zipWithFB #-}
 zipWithFB :: (a -> b -> c) -> (d -> e -> a) -> d -> e -> b -> c
-zipWithFB c f x y r = (x `f` y) `c` r
+zipWithFB c f = \x y r -> (x `f` y) `c` r
 
 {-# RULES
 "zipWith"       [~1] forall f xs ys.    zipWith f xs ys = build (\c n -> foldr2 (zipWithFB c f) n xs ys)