Re: [GHC] #4261: Add strict version of foldlWithKey to Map
#4261: Add strict version of foldlWithKey to Map -+-- Reporter: tibbe | Owner: Type: proposal | Status: new Priority: normal| Component: libraries (other) Version:|Keywords: Testcase:| Blockedby: Os: Unknown/Multiple |Blocking: Architecture: Unknown/Multiple | Failure: None/Unknown -+-- Comment(by tibbe): Discussion here: http://www.mail-archive.com/glasgow-haskell-bugs@haskell.org/msg28178.html -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/4261#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #4261: Add strict version of foldlWithKey to Map
#4261: Add strict version of foldlWithKey to Map --+- Reporter: tibbe | Owner: Type: proposal | Status: closed Priority: normal| Component: libraries (other) Version:| Resolution: duplicate Keywords:| Testcase: Blockedby:| Os: Unknown/Multiple Blocking:| Architecture: Unknown/Multiple Failure: None/Unknown | --+- Changes (by tibbe): * status: new = closed * resolution: = duplicate -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/4261#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #4261: Add strict version of foldlWithKey to Map
#4261: Add strict version of foldlWithKey to Map --+- Reporter: tibbe | Owner: Type: proposal | Status: closed Priority: normal| Component: libraries (other) Version:| Resolution: duplicate Keywords:| Testcase: Blockedby:| Os: Unknown/Multiple Blocking:| Architecture: Unknown/Multiple Failure: None/Unknown | --+- Comment(by tibbe): Superseded by #4278 -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/4261#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
[GHC] #4261: Add strict version of foldlWithKey to Map
#4261: Add strict version of foldlWithKey to Map
-+--
Reporter: tibbe | Owner:
Type: proposal | Status: new
Priority: normal| Component: libraries (other)
Version:|Keywords:
Testcase:| Blockedby:
Os: Unknown/Multiple |Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
-+--
There's currently no strict left (pre-order) fold for `Map`s, making it
impractical to do simple things like summing all the values in the map.
The attached patch adds a strict `foldlWithKeys'` function that generates
optimal core for code like:
{{{
module Test (test) where
import qualified Data.Map as M
test :: M.Map Int Int - Int
test m = M.foldlWithKey' (\n k v - n + k + v) 0 m
}}}
If we look at the core we see that the `Int` accumulator is unboxed like
we'd hope:
{{{
test_$s$wgo2 :: Data.Map.Map Int Int - Int# - Int#
test_$s$wgo2 =
\ (sc_smi :: Data.Map.Map Int Int)
(sc1_smj :: Int#) -
case sc_smi of _ {
Data.Map.Tip - sc1_smj;
Data.Map.Bin _ kx_ali x_alj l_alk r_all -
case test_$s$wgo2 l_alk sc1_smj of ww_slW { __DEFAULT -
case kx_ali of _ { I# y_alD -
case x_alj of _ { I# y1_XlT -
test_$s$wgo2
r_all (+# (+# ww_slW y_alD) y1_XlT)
}
}
}
}
$wtest :: Data.Map.Map Int Int - Int#
$wtest =
\ (w_slZ :: Data.Map.Map Int Int) -
test_$s$wgo2 w_slZ 0
test :: Data.Map.Map Int Int - Int
test =
__inline_me (\ (w_slZ :: Data.Map.Map Int Int) -
case $wtest w_slZ of ww_sm2 { __DEFAULT -
I# ww_sm2
})
}}}
Discussion deadline: 2 weeks
--
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/4261
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler
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