Question about specialization

[Harendra Kumar]

I am in the middle of a refactor. I will file a ticket once I am done.

On Mon, 6 Sept 2021 at 20:17, Simon Peyton Jones <simonpj at microsoft.com>
wrote:

> Harendra
>
>
>
> That comes as a surprise to me.  Could you possibly make a repo case, and
> say what version of the compiler does, and does not, specialise the
> function?
>
>
>
> File it as a ticket … to me it looks like a bug.
>
>
>
> Thanks
>
>
>
> Simon
>
>
>
> *From:* ghc-devs <ghc-devs-bounces at haskell.org> *On Behalf Of *Harendra
> Kumar
> *Sent:* 06 September 2021 14:11
> *To:* ghc-devs at haskell.org
> *Subject:* Question about specialization
>
>
>
> Hi GHC devs,
>
>
>
> I have a simple program using the streamly library, as follows, the whole
> code is in the same module:
>
>
>
> {-# INLINE iterateState #-}
> {-# SPECIALIZE iterateState :: Int -> SerialT (StateT Int IO) Int #-}
> iterateState :: MonadState Int m => Int -> SerialT m Int
> iterateState n = do
>     x <- get
>     if x > n
>     then do
>         put (x - 1)
>         iterateState n
>     else return x
>
>
>
> main :: IO ()
> main = do
>     State.evalStateT (S.drain (iterateState 0)) 100000
>
>
>
> Earlier the SPECIALIZE pragma was not required on iterateState, but after
> some refactoring in the library (the monad bind of SerialT changed a bit),
> this program now requires a SPECIALIZE on iterateState to trigger
> specialization, just INLINE also does not help.
>
>
>
> My question is whether this may be expected in some conditions or is this
> something which can be considered a bug in the compiler? I am also curious
> what specifically could have made the compiler not specialize this anymore,
> is it the size of the function or some other threshold?
>
>
>
> Thanks,
>
> Harendra
>
>
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/ghc-devs/attachments/20210907/1f371fbb/attachment.html>