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Prepare for specialization of Data.List #762

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Merged
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Jan 24, 2021
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Prepare for specialization of Data.List #762

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eb2e39c
Implement foldMap for ViewL
phadej Jan 19, 2021
b55d01a
Prepare containers to specialization of Data.List
phadej Jan 19, 2021
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4 changes: 2 additions & 2 deletions containers/src/Data/Graph.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,7 @@ import Data.Array.Unboxed ( UArray )
#else
import qualified Data.Array as UA
#endif
import Data.List
import qualified Data.List as L
#if MIN_VERSION_base(4,9,0)
import Data.Functor.Classes
#endif
Expand Down Expand Up @@ -442,7 +442,7 @@ graphFromEdges edges0
where
max_v = length edges0 - 1
bounds0 = (0,max_v) :: (Vertex, Vertex)
sorted_edges = sortBy lt edges0
sorted_edges = L.sortBy lt edges0
edges1 = zipWith (,) [0..] sorted_edges

graph = array bounds0 [(,) v (mapMaybe key_vertex ks) | (,) v (_, _, ks) <- edges1]
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9 changes: 8 additions & 1 deletion containers/src/Data/Sequence/Internal.hs
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Expand Up @@ -202,7 +202,6 @@ import Prelude hiding (
null, length, lookup, take, drop, splitAt, foldl, foldl1, foldr, foldr1,
scanl, scanl1, scanr, scanr1, replicate, zip, zipWith, zip3, zipWith3,
unzip, takeWhile, dropWhile, iterate, reverse, filter, mapM, sum, all)
import qualified Data.List
import Control.Applicative (Applicative(..), (<$>), (<**>), Alternative,
liftA2, liftA3)
import qualified Control.Applicative as Applicative
Expand All @@ -212,6 +211,11 @@ import Data.Monoid (Monoid(..))
import Data.Functor (Functor(..))
import Utils.Containers.Internal.State (State(..), execState)
import Data.Foldable (Foldable(foldl, foldl1, foldr, foldr1, foldMap, foldl', foldr'), toList)
import qualified Data.Foldable as F

#if !(__GLASGOW_HASKELL__ >= 708)
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@sjakobi sjakobi Jan 20, 2021

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Intuitively I'd prefer if CPP for base features was done with MIN_VERSION_base. I find it hard to remember the base version numbers though, so I wouldn't mind if we'd keep using __GLASGOW_HASKELL__.

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@treeowl treeowl Jan 20, 2021

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Definitely should use MIN_VERSION_base for this. Is there any reasonable way to avoid CPP for this altogether?

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@phadej phadej Jan 20, 2021

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Because he use of Data.List in the file is on __GLASGOW_HASKELL__ >= 708. https://github.com/haskell/containers/blob/master/containers/src/Data/Sequence/Internal.hs#L4388-L4392

I'm not keen to change / audit the CPP usage. __GLASGOW_HASKELL_ >= 708 is as good as MIN_VERSION_base to guard coerce usage.

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@phadej phadej Jan 20, 2021

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To be clear: say how you want this to be changed. I think the only way to make this nice is to drop pre-GHC-7.8 support (i.e. 7.6). But that rather be done in a separate patch going though whole of containers.

import qualified Data.List
#endif

#if MIN_VERSION_base(4,9,0)
import qualified Data.Semigroup as Semigroup
Expand Down Expand Up @@ -2192,6 +2196,9 @@ instance Functor ViewL where
fmap f (x :< xs) = f x :< fmap f xs

instance Foldable ViewL where
foldMap _ EmptyL = mempty
foldMap f (x :< xs) = f x <> foldMap f xs

foldr _ z EmptyL = z
foldr f z (x :< xs) = f x (foldr f z xs)

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