On 07/31/2012 12:04 AM, Artyom Kazak wrote:

Евгений Пермяков писал в своём письме Mon, 30 Jul 2012 09:47:48 +0300:

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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#:

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addIntC# :: Int# -> Int# -> (#Int#, Int##) Add with carry. First member of result is (wrapped) sum; second member is 0 iff no overflow occured.

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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@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.

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 On Tue, Jul 31, 2012 at 1:56 AM, Ryan Ingram wrote:

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

On Mon, Jul 30, 2012 at 1:43 PM, Евгений Пермяков wrote:

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On 07/31/2012 12:04 AM, Artyom Kazak wrote:

...

Евгений Пермяков 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@haskell.org http://www.haskell.org/**mailman/listinfo/haskell-cafehttp://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.

______________________________**_________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/**mailman/listinfo/haskell-cafehttp://www.haskell.org/mailman/listinfo/haskell-cafe