GitLab

Make `words` a good producer and `unwords` a good consumer for list
fusion. Thus `unwords . words` will avoid producing an intermediate list
of words, although it will produce each individual word.

Make `unwords` slightly lazier, so that
`unwords (s : undefined) = s ++ undefined` instead of `= undefined`.

Reviewed By: austin

Differential Revision: https://phabricator.haskell.org/D375

This makes nub and nubBy behave as specified in the Haskell 98 Report.

This reverts 0ad9def5, and
fixes #3280, #7913 and #2528 (properly).

Before this change, the output of `T2528` was (4x wrong):
```
[A,B]
[1,2]
False
False
```

Reviewed By: dfeuer, ekmett, austin, hvr

Differential Revision: https://phabricator.haskell.org/D238

This increases the chance of good code after fusing a left fold. See
ticket #7994 and the new Note [Left folds via right fold]

Differential Revision: https://phabricator.haskell.org/D393

This gets rid of all hand-unboxing in `GHC.List` and moves `Foldable`
requirements from `Data.OldList` into `GHC.List` (preparatory work for
addressing #9716).  Specifically, this moves the definition of
`maximum`, `minimum`, `foldl'`, `foldl1`, `foldl1'`, `sum`, and
`product` into `GHC.List` (which now needs to import `GHC.Num`)

Make `take`, `drop`, `length`, and `!!` generally saner (see also #9510)

Performance overall seems minimally affected. Some things go up; some
things go down; nothing moves horribly much. The code is much easier to
read.

Differential Revision: https://phabricator.haskell.org/D380

The new implementation avoids reversing the "haystack" list, which can be
very expensive.

Reviewed By: ekmett

Differential Revision: https://phabricator.haskell.org/D330

Summary:
Steal the findIndices implementation from Data.Sequence, that can
participate in fold/build fusion

Reviewers: nomeata, austin

Reviewed By: nomeata, austin

Subscribers: thomie, carter, ezyang, simonmar

Differential Revision: https://phabricator.haskell.org/D345

Reviewed By: nomeata, austin
Differential Revision: https://phabricator.haskell.org/D325

Fixes #9345. Use a modified banker's queue to achieve amortized optimal
performance for inits. The previous implementation was extremely slow.

Reviewed By: nomeata, ekmett, austin

Differential Revision: https://phabricator.haskell.org/D329

This fixes #9502.

This renames the Data.List module to Data.OldList, and puts a new
Data.List module into its place re-exporting all list functions.

The plan is to leave the monomorphic versions of the list functions in
Data.OldList to help smooth the transition.

The new Data.List module then will simply re-export entities from
Data.OldList and Data.Foldable.

This refactoring has been placed in a separate commit to be able to
better isolate any regressions caused by the actual list function
generalisations when implementing #9586

This also updates the haskell2010, haskell98, and array submodules

Reviewed By: austin, ekmett

Differential Revision: https://phabricator.haskell.org/D228

Since we now had to major bump due to AMP being landed, `base-4.7.1.0` is not
gonna happen, as we're going straight for a `base-4.8.0.0` release.

[skip ci] since this is a doc-only change

Summary:
to allow GHC to maybe remove the Maybe. See the code comment for more
commentary. This fixes #9369.

Test Plan: see what happens on ghcspeed (once it is merged)

Reviewers: austin

Reviewed By: austin

Subscribers: simonmar, ezyang, carter

Differential Revision: https://phabricator.haskell.org/D198

GHC Trac Issues: #9369

Summary:
As discussed in
http://www.haskell.org/pipermail/libraries/2014-July/023314.html and
submitted at #9550.

Test Plan: Submit to phab, see what happens.

Reviewers: austin

Subscribers: simonmar, ezyang, carter

Differential Revision: https://phabricator.haskell.org/D195

GHC Trac Issues: #9550

Test Plan: validate

Reviewers: austin

Reviewed By: austin

Subscribers: phaskell, simonmar, relrod, carter

Differential Revision: https://phabricator.haskell.org/D77

Update several old

  http://hackage.haskell.org/trac/ghc

URLs references to the current

  http://ghc.haskell.org/trac/ghc

URLs.
Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

`sortOn` sorts a list by comparing the results of a key function applied to each
element.  `sortOn f` is equivalent to `sortBy . comparing f`, but has the
performance advantage of only evaluating `f` once for each element in the
input list.

Historical note: This was already proposed in 2008 as part of

  http://www.haskell.org/pipermail/libraries/2008-October/010797.html

It was, however, the recent re-attempt

  http://www.haskell.org/pipermail/libraries/2014-April/022489.html

that let `sortOn` make it into base at last. Maybe the other functions
mentioned in #2659 might be worth reconsidering as well.

in order to allow fusion of the foldr in the foldl in the foldl' therein.

together with the call arity analysis and the following patch (about inlining
maximum), we get nice benefits from fusing foldl and foldl' with good
producers:

                Min          -0.1%    -74.5%     -6.8%     -8.3%    -50.0%
                Max          +0.2%      0.0%    +38.5%    +38.5%      0.0%
     Geometric Mean          -0.0%     -4.1%     +7.7%     +7.7%     -0.8%

Because this depends on a compiler optimisation, we have to watch out for cases
where this is not an improvements, and whether they occur in the wild.

This commit retroactively adds `/Since: 4.5.[01].0/` annotations to symbols
newly added/exposed in `base-4.5.[01].0` (as shipped with GHC 7.4.[12]).

See also 6368362f which adds the respective annotation for symbols newly
added in `base-4.7.0.0` (that goes together with GHC 7.8.1).
Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

Now that HUGS and NHC specific code has been removed, this commit "folds"
the now redundant `#if((n)def)`s containing `__GLASGOW_HASKELL__`.  This
renders `base` officially GHC only.

This commit also removes redundant `{-# LANGUAGE CPP #-}`.
Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

Wording suggested by Bart Massey.

This was causing the bad behaviour in Trac #7507,
because 'sum' wasn't getting specialised to Int64.

It also deals with Trac #4321, which had the same cause.

This has a big effect on some nofib programs too:

--------------------------------------------------------------------------------
        Program           Allocs   Runtime   Elapsed  TotalMem
------------------------------------------------------------------------
     bernouilli            -2.6%     -2.0%     -2.0%     +0.0%
           fft2           -23.8%      0.09      0.09    -16.7%
          fluid            -4.4%      0.01      0.01     +0.0%
         hidden            -3.2%     +2.1%     +1.8%     +0.0%
      integrate           -38.0%    -47.7%    -47.7%     -1.0%
           x2n1           -30.2%      0.01      0.01    -50.0%
------------------------------------------------------------------------
            Min           -38.0%    -47.7%    -47.7%    -50.0%
            Max            +0.4%    +11.2%    +11.8%     +6.9%
 Geometric Mean            -1.3%     +0.2%     +0.2%     -0.8%

No changes, just using nicer type variable names

These comments are rather less useful now that haddock can give docs
with the same informatino in the module synopsis.

Having to maintain them when making changes to the library is a pain,
and when people forget about doing so there is nothing that checks that
the comments are right, so mistakes tend to linger.

Of the comments that my script detected, 78 of 684 were already
incorrect in one way or another, e.g. missing context:
    Text.Show.showsPrec
    Comment type: Int -> a -> ShowS
    Actual type:  Show a => Int -> a -> ShowS
wrong context:
    Numeric.readInt
    Comment type: Integral a => a -> (Char -> Bool) -> (Char -> Int) -> ReadS a
    Actual type:  Num a => a -> (Char -> Bool) -> (Char -> Int) -> ReadS a
not following a class change (e.g. Num losing its Eq superclass):
    Text.Read.Lex.readOctP
    Comment type: Num a => ReadP a
    Actual type:  (Eq a, Num a) => ReadP a
not following the Exceptions change:
    GHC.Conc.childHandler
    Comment type: Exception -> IO ()
    Actual type:  SomeException -> IO ()
or just always been wrong:
    GHC.Stable.deRefStablePtr
    Comment type: StablePtr a -> a
    Actual type:  StablePtr a -> IO a

Mention which list is the source
of the elements in the resulting list.

Converted from darcs patches from Bas van Dijk <v.dijk.bas@gmail.com>

Previously: tails _|_ = _|_
Now:        tails _|_ = _|_ : _|_

Previously: inits _|_ = _|_
Now:        inits _|_ = [] : _|_

Add explicit {-# LANGUAGE xxx #-} pragmas to each module, that say
what extensions that module uses.  This makes it clearer where
different extensions are used in the (large, variagated) base package.

Now base.cabal doesn't need any extensions field

Thanks to Bas van Dijk for doing all the work.

Make selector thunks visible to GHC to fix a space leak in lines.

A lazier implementation of intersperse, and consequentially intercalate, to
avoid space leaks.

Add shortcuts to intersectBy for empty list arguments.
In addition to being faster in that case, more inputs yield defined results.
Treats ticket #4323