\begin{code}
+{-# LANGUAGE NoImplicitPrelude, NoBangPatterns, MagicHash, UnboxedTuples #-}
{-# OPTIONS_GHC -funbox-strict-fields #-}
-{-# LANGUAGE NoImplicitPrelude, NoBangPatterns #-}
{-# OPTIONS_HADDOCK hide #-}
+
-----------------------------------------------------------------------------
-- |
-- Module : GHC.Arr
-- An implementation is entitled to assume the following laws about these
-- operations:
--
--- * @'inRange' (l,u) i == 'elem' i ('range' (l,u))@
+-- * @'inRange' (l,u) i == 'elem' i ('range' (l,u))@ @ @
--
-- * @'range' (l,u) '!!' 'index' (l,u) i == i@, when @'inRange' (l,u) i@
--
--- * @'map' ('index' (l,u)) ('range' (l,u))) == [0..'rangeSize' (l,u)-1]@
+-- * @'map' ('index' (l,u)) ('range' (l,u))) == [0..'rangeSize' (l,u)-1]@ @ @
--
--- * @'rangeSize' (l,u) == 'length' ('range' (l,u))@
+-- * @'rangeSize' (l,u) == 'length' ('range' (l,u))@ @ @
--
-- Minimal complete instance: 'range', 'index' and 'inRange'.
--
-- | The type of immutable non-strict (boxed) arrays
-- with indices in @i@ and elements in @e@.
--- The Int is the number of elements in the Array.
-data Ix i => Array i e
- = Array !i -- the lower bound, l
- !i -- the upper bound, u
- !Int -- a cache of (rangeSize (l,u))
- -- used to make sure an index is
- -- really in range
- (Array# e) -- The actual elements
+data Array i e
+ = Array !i -- the lower bound, l
+ !i -- the upper bound, u
+ !Int -- a cache of (rangeSize (l,u))
+ -- used to make sure an index is
+ -- really in range
+ (Array# e) -- The actual elements
-- | Mutable, boxed, non-strict arrays in the 'ST' monad. The type
-- arguments are as follows:
--
-- Because the indices must be checked for these errors, 'array' is
-- strict in the bounds argument and in the indices of the association
--- list, but nonstrict in the values. Thus, recurrences such as the
+-- list, but non-strict in the values. Thus, recurrences such as the
-- following are possible:
--
-- > a = array (1,100) ((1,1) : [(i, i * a!(i-1)) | i <- [2..100]])
{-# INLINE fill #-}
fill :: MutableArray# s e -> (Int, e) -> STRep s a -> STRep s a
-fill marr# (I# i#, e) next s1# =
- case writeArray# marr# i# e s1# of { s2# ->
- next s2# }
+-- NB: put the \s after the "=" so that 'fill'
+-- inlines when applied to three args
+fill marr# (I# i#, e) next
+ = \s1# -> case writeArray# marr# i# e s1# of
+ s2# -> next s2#
{-# INLINE done #-}
done :: Ix i => i -> i -> Int -> MutableArray# s e -> STRep s (Array i e)
-done l u n marr# s1# =
- case unsafeFreezeArray# marr# s1# of
- (# s2#, arr# #) -> (# s2#, Array l u n arr# #)
+-- See NB on 'fill'
+done l u n marr#
+ = \s1# -> case unsafeFreezeArray# marr# s1# of
+ (# s2#, arr# #) -> (# s2#, Array l u n arr# #)
-- This is inefficient and I'm not sure why:
-- listArray (l,u) es = unsafeArray (l,u) (zip [0 .. rangeSize (l,u) - 1] es)
assocs arr@(Array l u _ _) =
[(i, arr ! i) | i <- range (l,u)]
--- | The 'accumArray' deals with repeated indices in the association
+-- | The 'accumArray' function deals with repeated indices in the association
-- list using an /accumulating function/ which combines the values of
-- associations with the same index.
-- For example, given a list of values of some index type, @hist@
{-# INLINE adjust #-}
adjust :: (e -> a -> e) -> MutableArray# s e -> (Int, a) -> STRep s b -> STRep s b
-adjust f marr# (I# i#, new) next s1# =
- case readArray# marr# i# s1# of
- (# s2#, old #) ->
- case writeArray# marr# i# (f old new) s2# of
- s3# -> next s3#
+-- See NB on 'fill'
+adjust f marr# (I# i#, new) next
+ = \s1# -> case readArray# marr# i# s1# of
+ (# s2#, old #) ->
+ case writeArray# marr# i# (f old new) s2# of
+ s3# -> next s3#
-- | Constructs an array identical to the first argument except that it has
-- been updated by the associations in the right argument.