Simon Peyton-Jones wrote:
If it's tail recursive it'll be compiled to a loop. You don't need a pragma.
The ~pragma is in order to make an error if it's not a loop. Same way as
we don't need type-signatures in export lists and their only purpose is
to cause errors when something unexpected an
Some compilers unroll recursive functions by inlining them N times, for some fixed N (say 3 or so).
This reduces the loop overheads. GHC doesn't do this, although it'd be nice, because it makes
repeated traversals of the code, and it's hard to spot when the function has been unrolled 3 times
an
On Wed, Aug 01, 2007 at 09:42:54AM +0200, Georg Martius wrote:
> Hi,
>
> I am sorry for using the wrong terminology here. Let me ask again:
> Does it sound reasonable to extend the compiler with a pragma that specifies
> that a certain function should be compiled to a loop? And if the compiler ca
ll g inside the loop.
Simon
| -Original Message-
| From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
| Behalf Of Georg Martius
| Sent: 01 August 2007 08:43
| To: Simon Peyton-Jones; Glasgow-haskell-users@haskell.org
| Subject: Re: Annotation for unfolding wanted
|
| Hi,
|
| I am sorry for usin
Hi,
I am sorry for using the wrong terminology here. Let me ask again:
Does it sound reasonable to extend the compiler with a pragma that specifies
that a certain function should be compiled to a loop? And if the compiler can
not do it, it helps with some error message.
Regards!
Georg
| > {-# INLINE f #-}
| > f x y z = ... f x' y' z' ...
| >
| > into this:
| >
| > {-# INLINE f #-}
| > f x y z = f' x y z
| >where f' x y z = ... f' x' y' z' ...
| >
| > That is, shoving (all of) the recursion in a level. Then inlining f
| > results in a fresh loop, which presumably can be spe
On Tue, 2007-07-31 at 10:36 -0400, Jan-Willem Maessen wrote:
> I think what's meant here is translating something like this:
>
> {-# INLINE f #-}
> f x y z = ... f x' y' z' ...
>
> into this:
>
> {-# INLINE f #-}
> f x y z = f' x y z
>where f' x y z = ... f' x' y' z' ...
>
> That is, shov
On Jul 31, 2007, at 10:20 AM, Simon Peyton-Jones wrote:
| However my point was more on a semantic point of view: If I write
a function
| in a recursive way, but actually do nothing else than a loop, I
would like
| a) that the compiler unrolls it to a loop and
| b) that I can specify such a
| However my point was more on a semantic point of view: If I write a function
| in a recursive way, but actually do nothing else than a loop, I would like
| a) that the compiler unrolls it to a loop and
| b) that I can specify such a requirement, while violating it emits an error.
What does it me
Hi Simon,
thanks for the answer! I see why inlining is not a good idea, but why is it
not unfolded. I mean we don't need any true recursion if the function is
tail-recursive or am I mistaken?
However my point was more on a semantic point of view: If I write a function
in a recursive way, but ac
| I was wondering why we don't have an annotation or pragma for function to tell
| the compiler that we _need_ this particular recursive function to be unfolded.
| If the compiler cannot do this for some reason it should produce an error
| message to help you modifying your code. I have regularly p
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