Can someone tell me if there are any primitives, that used to detect machine type overflows, in ghc haskell ? I perfectly understand, that I can build something based on preconditioning of variables, but this will kill any performance, if needed.
Евгений Пермяков <permeakra <at> gmail.com> писал в своём письме Mon, 30 Jul 2012 09:47:48 +0300: > Can someone tell me if there are any primitives, that used to detect > machine type overflows, in ghc haskell ? I perfectly understand, that I > can build something based on preconditioning of variables, but this will > kill any performance, if needed. In GHC.Prim — primitives addIntC# and subIntC#: > addIntC# :: Int# -> Int# -> (#Int#, Int##) > Add with carry. First member of result is (wrapped) sum; second member > is 0 iff no overflow occured. > subIntC# :: Int# -> Int# -> (#Int#, Int##) > Subtract with carry. First member of result is (wrapped) difference; > second member is 0 iff no overflow occured. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe <at> haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
On 07/31/2012 12:04 AM, Artyom Kazak wrote: > Евгений Пермяков <permeakra <at> gmail.com> писал в своём письме Mon, 30 > Jul 2012 09:47:48 +0300: > >> Can someone tell me if there are any primitives, that used to detect >> machine type overflows, in ghc haskell ? I perfectly understand, that >> I can build something based on preconditioning of variables, but this >> will kill any performance, if needed. > > In GHC.Prim — primitives addIntC# and subIntC#: > >> addIntC# :: Int# -> Int# -> (#Int#, Int##) >> Add with carry. First member of result is (wrapped) sum; second >> member is 0 iff no overflow occured. > >> subIntC# :: Int# -> Int# -> (#Int#, Int##) >> Subtract with carry. First member of result is (wrapped) difference; >> second member is 0 iff no overflow occured. > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe <at> haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe Still no way to detect overflow in *. Strangely enough, I found some relevant descriptions in *.pp in dev branch, so I expect them in 7.6.1. They applies to native-size Word and Int only.(Continue reading)
Sure, but it's easy to roll your own from those primitives:
{-# LANGUAGE MagicHash, UnboxedTuples #-}
import GHC.Exts
addCarry :: Int -> Int -> (Int, Bool)
addCarry (I# x) (I# y) = case addIntC# x y of
(# s, c #) -> case c of
0# -> (I# s, False)
_ -> (I# s, True)
or something along those lines.
-- ryan
Still no way to detect overflow in *.On 07/31/2012 12:04 AM, Artyom Kazak wrote:Евгений Пермяков <permeakra <at> gmail.com> писал в своём письме Mon, 30 Jul 2012 09:47:48 +0300:Can someone tell me if there are any primitives, that used to detect machine type overflows, in ghc haskell ? I perfectly understand, that I can build something based on preconditioning of variables, but this will kill any performance, if needed.
In GHC.Prim — primitives addIntC# and subIntC#:addIntC# :: Int# -> Int# -> (#Int#, Int##)
Add with carry. First member of result is (wrapped) sum; second member is 0 iff no overflow occured.
subIntC# :: Int# -> Int# -> (#Int#, Int##)
Subtract with carry. First member of result is (wrapped) difference; second member is 0 iff no overflow occured.
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Strangely enough, I found some relevant descriptions in *.pp in dev branch, so I expect them in 7.6.1. They applies to native-size Word and Int only.
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Actually, looking at the docs, I'm not sure if case expressions work on unboxed ints; you may need
addCarry (I# x) (I# y) = case addIntC# x y of (# s, c #) -> (I# s, c /=# 0#)
which is somewhat simpler anyways.
-- ryan
Sure, but it's easy to roll your own from those primitives:
{-# LANGUAGE MagicHash, UnboxedTuples #-}
import GHC.Exts
addCarry :: Int -> Int -> (Int, Bool)
addCarry (I# x) (I# y) = case addIntC# x y of
(# s, c #) -> case c of
0# -> (I# s, False)
_ -> (I# s, True)
or something along those lines.
-- ryanOn Mon, Jul 30, 2012 at 1:43 PM, Евгений Пермяков <permeakra <at> gmail.com> wrote:Still no way to detect overflow in *.On 07/31/2012 12:04 AM, Artyom Kazak wrote:Евгений Пермяков <permeakra <at> gmail.com> писал в своём письме Mon, 30 Jul 2012 09:47:48 +0300:Can someone tell me if there are any primitives, that used to detect machine type overflows, in ghc haskell ? I perfectly understand, that I can build something based on preconditioning of variables, but this will kill any performance, if needed.
In GHC.Prim — primitives addIntC# and subIntC#:addIntC# :: Int# -> Int# -> (#Int#, Int##)
Add with carry. First member of result is (wrapped) sum; second member is 0 iff no overflow occured.
subIntC# :: Int# -> Int# -> (#Int#, Int##)
Subtract with carry. First member of result is (wrapped) difference; second member is 0 iff no overflow occured.
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe <at> haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
Strangely enough, I found some relevant descriptions in *.pp in dev branch, so I expect them in 7.6.1. They applies to native-size Word and Int only.
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Haskell-Cafe <at> haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe <at> haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Hi. On Mon, Jul 30, 2012 at 8:47 AM, Евгений Пермяков <permeakra <at> gmail.com> wrote: > Can someone tell me if there are any primitives, that used to detect machine > type overflows, in ghc haskell ? I perfectly understand, that I can build > something based on preconditioning of variables, but this will kill any > performance, if needed. There's http://hackage.haskell.org/package/safeint/ It's not implemented quite as efficiently as it theoretically could be, but it might do more or less what you want. Cheers, Andres -- -- Andres Löh, Haskell Consultant Well-Typed LLP, http://www.well-typed.com _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe <at> haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
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