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Today's Topics:
1. Re: Understanding syntax problems (aditya siram)
2. Re: Understanding syntax problems (Stephen Tetley)
3. Re: Understanding syntax problems (Nathan Huesken)
4. Re: Understanding syntax problems (Daniel Fischer)
5. Re: Understanding syntax problems (aditya siram)
6. Re: Understanding syntax problems (Daniel Fischer)
7. profiling weirdness? (Thomas)
8. Re: profiling weirdness? (Daniel Fischer)
9. Compiling Test.hs from reactive-fieldtrip (Nathan Huesken)
10. Re: Compiling Test.hs from reactive-fieldtrip (aditya siram)
----------------------------------------------------------------------
Message: 1
Date: Tue, 8 Jun 2010 12:49:23 -0500
From: aditya siram <[email protected]>
Subject: Re: [Haskell-beginners] Understanding syntax problems
To: Nathan Huesken <[email protected]>
Cc: Biginners Haskell Mailinglist <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
A "type" can be both a synonym for both another type or a function. For example:
type ProcessIntList = [Int] -> [Int]
add_one :: ProcessIntList
add_one = map ((+) 1)
is the same as:
add_one :: [Int] -> [Int]
add_one = map ((+) 1)
-deech
On 6/8/10, Nathan Huesken <[email protected]> wrote:
> Hi,
>
> Reading this:
> http://netsuperbrain.com/blog/posts/introducing-reactive-events/
>
> I stumble upon this:
>
> type BellMachine = Event () -> Event ()
>
> Google did not tell me, what this means.
> I understand
>
> type BellMachine = Event()
>
> but the rest is completely strange to me.
>
> What does it mean or where can I find out?
>
> Thanks!
> Nathan
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
>
------------------------------
Message: 2
Date: Tue, 8 Jun 2010 18:52:20 +0100
From: Stephen Tetley <[email protected]>
Subject: Re: [Haskell-beginners] Understanding syntax problems
To: Nathan Huesken <[email protected]>
Cc: Biginners Haskell Mailinglist <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
Hi
This is a typo - caused in the translation to HTML:
type BellMachine = Event () -> Event ()
A Bell Machine is a function from Event to Event.
Representing state machines as functions from their input to their
output is quite a common pattern in Haskell.
Best wishes
Stephen
------------------------------
Message: 3
Date: Tue, 8 Jun 2010 13:58:32 -0400
From: Nathan Huesken <[email protected]>
Subject: Re: [Haskell-beginners] Understanding syntax problems
To: Biginners Haskell Mailinglist <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=US-ASCII
Well, that makes complete sense.
Just out of curiosity, is it my browser or a problem with the site?
Regards,
Nathan
On Tue, 8 Jun 2010 18:52:20 +0100
Stephen Tetley <[email protected]> wrote:
> Hi
>
> This is a typo - caused in the translation to HTML:
>
> type BellMachine = Event () -> Event ()
>
> A Bell Machine is a function from Event to Event.
>
> Representing state machines as functions from their input to their
> output is quite a common pattern in Haskell.
>
>
> Best wishes
>
> Stephen
>
------------------------------
Message: 4
Date: Tue, 8 Jun 2010 20:00:50 +0200
From: Daniel Fischer <[email protected]>
Subject: Re: [Haskell-beginners] Understanding syntax problems
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
On Tuesday 08 June 2010 17:14:19, Nathan Huesken wrote:
> Hi,
>
> Reading this:
> http://netsuperbrain.com/blog/posts/introducing-reactive-events/
>
> I stumble upon this:
>
> type BellMachine = Event () -> Event ()
Html escaping hiccup (several more of that on the page).
It should be
type BellMachine = Event () -> Event ()
so BellMachine is an alias for the type of functions mapping an Event () to
an Event ().
>
> Google did not tell me, what this means.
> I understand
>
> type BellMachine = Event()
>
> but the rest is completely strange to me.
>
> What does it mean or where can I find out?
>
> Thanks!
> Nathan
------------------------------
Message: 5
Date: Tue, 8 Jun 2010 13:03:59 -0500
From: aditya siram <[email protected]>
Subject: Re: [Haskell-beginners] Understanding syntax problems
To: Daniel Fischer <[email protected]>
Cc: [email protected]
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
I've been doing way too much HTML - I automatically translated ~>
in my head. Ugh.
-deech
On 6/8/10, Daniel Fischer <[email protected]> wrote:
> On Tuesday 08 June 2010 17:14:19, Nathan Huesken wrote:
>> Hi,
>>
>> Reading this:
>> http://netsuperbrain.com/blog/posts/introducing-reactive-events/
>>
>> I stumble upon this:
>>
>> type BellMachine = Event () -> Event ()
>
> Html escaping hiccup (several more of that on the page).
>
> It should be
>
> type BellMachine = Event () -> Event ()
>
> so BellMachine is an alias for the type of functions mapping an Event () to
> an Event ().
>
>>
>> Google did not tell me, what this means.
>> I understand
>>
>> type BellMachine = Event()
>>
>> but the rest is completely strange to me.
>>
>> What does it mean or where can I find out?
>>
>> Thanks!
>> Nathan
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
>
------------------------------
Message: 6
Date: Tue, 8 Jun 2010 20:15:20 +0200
From: Daniel Fischer <[email protected]>
Subject: Re: [Haskell-beginners] Understanding syntax problems
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
On Tuesday 08 June 2010 19:58:32, Nathan Huesken wrote:
> Well, that makes complete sense.
> Just out of curiosity, is it my browser or a problem with the site?
Not your browser:
type</span> BellMachine <span style="color: #339933; font-weight:
bold;">=</span> Event <span style="color: green;">(</span><span
style="color: green;">)</span> <span style="color: #339933; font-
weight: bold;">-</span>&gt; Event <span style="color:
green;">(</span><span style="color: green;">)
See the &gt; ?
>
> Regards,
> Nathan
>
> On Tue, 8 Jun 2010 18:52:20 +0100
>
> Stephen Tetley <[email protected]> wrote:
> > Hi
> >
> > This is a typo - caused in the translation to HTML:
> >
> > type BellMachine = Event () -> Event ()
> >
> > A Bell Machine is a function from Event to Event.
> >
> > Representing state machines as functions from their input to their
> > output is quite a common pattern in Haskell.
> >
> >
> > Best wishes
> >
> > Stephen
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
------------------------------
Message: 7
Date: Wed, 09 Jun 2010 01:23:56 +0200
From: Thomas <[email protected]>
Subject: [Haskell-beginners] profiling weirdness?
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hello all!
Currently this is more of a curiosity for me rather than a real obstacle
to learn Haskell, but I'd appreciate any insight into this behaviour
nevertheless.
Given the (dumb, I know, but it's for illustration purpose) program:
---
import Data.Char
type Position = (Char, Integer)
sameSquare :: Position -> Position -> Bool
sameSquare p1 p2
= ssqHelper p1 p2
ssqHelper :: Position -> Position -> Bool
ssqHelper (r1, c1) (r2, c2)
| (((c1-1) `div` 3) == ((c2-1) `div` 3) && ((((ord r1) - 65)
`div` 3) == (((ord r2) - 65) `div` 3))) = True
| otherwise = False
main :: IO ()
main = print (sameSquare ('A', 2) ('B', 2))
---
If I compile this with profiling info and run the profiler all seems
well (independently of optimization settings). Now, if I comment the line
--ssqHelper :: Position -> Position -> Bool
and do the same (compile with profiling info) I can see rather
surprising results. While I'd expect exactly one call to ssqHelper for
every call to sameSquare this is actually only the case if compiled
without optimizations. Using -O2 when compiling I get a full 5 calls of
ssqHelper for every call to sameSquare.
I am unable to imagine an optimization that would be more efficient with
five calls instead of one. And I do not understand either what this has
to do with the type annotation. Within such a trivial program the
inferred type should be equivalent, shouldn't it?
Actually ghci generalizes slightly: Integral instead of Integer. But
that's no clue for me either...
BTW I'm using ghc 6.10.4. (In case it matters.)
Any hint would be appreciated.
Thanks,
Thomas
------------------------------
Message: 8
Date: Wed, 9 Jun 2010 02:41:29 +0200
From: Daniel Fischer <[email protected]>
Subject: Re: [Haskell-beginners] profiling weirdness?
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
On Wednesday 09 June 2010 01:23:56, Thomas wrote:
> Hello all!
>
> Currently this is more of a curiosity for me rather than a real obstacle
> to learn Haskell, but I'd appreciate any insight into this behaviour
> nevertheless.
>
> Given the (dumb, I know, but it's for illustration purpose) program:
> ---
> import Data.Char
>
> type Position = (Char, Integer)
>
> sameSquare :: Position -> Position -> Bool
> sameSquare p1 p2
> = ssqHelper p1 p2
>
> ssqHelper :: Position -> Position -> Bool
> ssqHelper (r1, c1) (r2, c2)
>
> | (((c1-1) `div` 3) == ((c2-1) `div` 3) && ((((ord r1) - 65)
>
> `div` 3) == (((ord r2) - 65) `div` 3))) = True
>
> | otherwise = False
>
> main :: IO ()
> main = print (sameSquare ('A', 2) ('B', 2))
> ---
>
> If I compile this with profiling info and run the profiler all seems
With -auto-all?
> well (independently of optimization settings). Now, if I comment the
> line --ssqHelper :: Position -> Position -> Bool
> and do the same (compile with profiling info) I can see rather
> surprising results. While I'd expect exactly one call to ssqHelper for
> every call to sameSquare this is actually only the case if compiled
> without optimizations. Using -O2 when compiling I get a full 5 calls of
> ssqHelper for every call to sameSquare.
No, you don't, fortunately. It's an artifact of the code generation. When
you compile with optimisations, GHC generates a specialised version of
ssqHelper and it inserts several SCC pragmas in that (as well as in the
polymorphic version if ssqHelper is exported), while without optimisations
it only generates a specialised wrapper and inserts only one SCC pragma in
the polymorphic worker.
When the code comes across an SCC pragma, that counts as one entry (NB,
entries /= calls).
So the unoptimised code meets only one pragma per call, hence one entry.
The optimised code meets several pragmas (the number depends on the code-
path taken) and records several entries per call.
>
> I am unable to imagine an optimization that would be more efficient with
> five calls instead of one. And I do not understand either what this has
> to do with the type annotation. Within such a trivial program the
> inferred type should be equivalent, shouldn't it?
Not quite. No optimisations means GHC generates polymorphic code without
the type signature. Only with optimisations does it care that ssqHelper is
not exported (I assume you didn't give a module declaration, so it's taken
to be "module Main (main) where") and used only at the one type, so
produces only the specialised version [or two versions if ssqHelper is
exported].
> Actually ghci generalizes slightly: Integral instead of Integer. But
> that's no clue for me either...
>
> BTW I'm using ghc 6.10.4. (In case it matters.)
Not much. With 6.12, you get only 3 entries to ssqHelper per sameSquare
returning True.
>
> Any hint would be appreciated.
> Thanks,
> Thomas
>
------------------------------
Message: 9
Date: Tue, 8 Jun 2010 22:13:32 -0400
From: Nathan Huesken <[email protected]>
Subject: [Haskell-beginners] Compiling Test.hs from reactive-fieldtrip
To: Biginners Haskell Mailinglist <[email protected]>
Message-ID: <20100608221332.7feaa...@samzwo>
Content-Type: text/plain; charset=US-ASCII
Hi,
I am trying to compile the Test.hs form reactive-fieltrip.
I did:
ghc --make
Test
(22:09) [1 of 3] Compiling FRP.Reactive.FieldTrip.Adapter
( FRP/Reactive/FieldTrip/Adapter.hs, FRP/Reactive/FieldTrip/Adapter.o )
[2 of 3] Compiling FRP.Reactive.FieldTrip ( FRP/Reactive/FieldTrip.hs,
FRP/Reactive/FieldTrip.o ) [3 of 3] Compiling Test
( Test.hs, Test.o )
Wonderfull, only it is not giving me an executable, only Test.o.
It has a main function, so how can I compile it?
Thanks!
nathan
------------------------------
Message: 10
Date: Tue, 8 Jun 2010 21:55:38 -0500
From: aditya siram <[email protected]>
Subject: Re: [Haskell-beginners] Compiling Test.hs from
reactive-fieldtrip
To: Nathan Huesken <[email protected]>
Cc: Biginners Haskell Mailinglist <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
To compile an executable, tack on -o <executable_name>, so for instance,
ghc --make HelloWorld.hs -o HelloWorld
creates an executable called `HelloWorld'.
-deech
On 6/8/10, Nathan Huesken <[email protected]> wrote:
> Hi,
>
> I am trying to compile the Test.hs form reactive-fieltrip.
> I did:
> ghc --make
> Test
> (22:09) [1 of 3] Compiling FRP.Reactive.FieldTrip.Adapter
> ( FRP/Reactive/FieldTrip/Adapter.hs, FRP/Reactive/FieldTrip/Adapter.o )
> [2 of 3] Compiling FRP.Reactive.FieldTrip ( FRP/Reactive/FieldTrip.hs,
> FRP/Reactive/FieldTrip.o ) [3 of 3] Compiling Test
> ( Test.hs, Test.o )
>
> Wonderfull, only it is not giving me an executable, only Test.o.
>
> It has a main function, so how can I compile it?
> Thanks!
> nathan
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
>
------------------------------
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