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Today's Topics:
1. Re: Generating Code To Embed in an Event Loop (Darrin Thompson)
2. Re: Need some advices about university (Brent Yorgey)
3. Forcing output of show (Hugo Ferreira)
4. Re: Forcing output of show (Daniel Fischer)
5. Re: Forcing output of show (Hugo Ferreira)
6. Re: Generating Code To Embed in an Event Loop (Stephen Tetley)
----------------------------------------------------------------------
Message: 1
Date: Wed, 26 Oct 2011 08:11:57 -0400
From: Darrin Thompson <[email protected]>
Subject: Re: [Haskell-beginners] Generating Code To Embed in an Event
Loop
To: Stephen Tetley <[email protected]>
Cc: [email protected]
Message-ID:
<cabe4vzwuei6kqfqxtwvdivgu1frcruk3zpnpnrv6taykjbw...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
On Tue, Oct 25, 2011 at 6:08 PM, Stephen Tetley <[email protected]>wrote:
> Pragmatically, code generation works well in domains where you have a
> succint input format and many candidates to generate - parser
> generators like YACC or Haskell's Happy are prime examples. If you
> don't have many candidates for generating, writing good libraries in
> the low-level language seems a more profficient use of one's time.
>
>
Can you elaborate on why? Is it because code generation is a lot harder than
it looks? Or that it's a lot of tedious work for just one output program?
--
Darrin
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Message: 2
Date: Wed, 26 Oct 2011 10:04:09 -0400
From: Brent Yorgey <[email protected]>
Subject: Re: [Haskell-beginners] Need some advices about university
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii
On Wed, Oct 26, 2011 at 01:56:05PM +0800, Zhi-Qiang Lei wrote:
> Hi,
>
> I'm making a plan to gain more computer knowledge (functional
> programming and Haskell especially) and a Master's degree in a
> university. Does anybody know which university in USA has good
> resources in this domain? Thanks.
The University of Pennsylvania has a good masters' degree program and
a great programming languages group -- although they are not really
connected (you would not get to study a whole lot of FP stuff while
doing the masters' degree). But of course you could come to the PL
group meetings.
-Brent
------------------------------
Message: 3
Date: Wed, 26 Oct 2011 15:23:20 +0100
From: Hugo Ferreira <[email protected]>
Subject: [Haskell-beginners] Forcing output of show
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-15; format=flowed
Hello,
Apologies for this newbie question.
I have a test function:
testLearnRules train = do
h <- IO.openFile train IO.ReadMode
c <- IO.hGetContents h
let proposedRules = instRules $ words c
let rs = take 10 $ M.assocs proposedRules
let _ = show rs
-- let _ = length rs
return ()
I realize that nothing is executed due to Haskell's
lazy evaluation. How can I force show to print
something to the screen?
Appreciate any pointers,
TIA,
Hugo F.
------------------------------
Message: 4
Date: Wed, 26 Oct 2011 16:29:52 +0200
From: Daniel Fischer <[email protected]>
Subject: Re: [Haskell-beginners] Forcing output of show
To: [email protected]
Message-ID: <[email protected]>
Content-Type: Text/Plain; charset="iso-8859-1"
On Wednesday 26 October 2011, 16:23:20, Hugo Ferreira wrote:
> Hello,
>
> Apologies for this newbie question.
> I have a test function:
>
> testLearnRules train = do
> h <- IO.openFile train IO.ReadMode
> c <- IO.hGetContents h
> let proposedRules = instRules $ words c
> let rs = take 10 $ M.assocs proposedRules
> let _ = show rs
> -- let _ = length rs
> return ()
>
> I realize that nothing is executed due to Haskell's
> lazy evaluation. How can I force show to print
> something to the screen?
You can't force show to rpint something, since show is a pure function not
involving IO.
However, testLearnRules does involve IO, so instead of
let _ = show rs
you could simply print it out,
print rs
-- equivalently, putStrLn (show rs)
>
> Appreciate any pointers,
>
> TIA,
> Hugo F.
------------------------------
Message: 5
Date: Wed, 26 Oct 2011 15:40:36 +0100
From: Hugo Ferreira <[email protected]>
Subject: Re: [Haskell-beginners] Forcing output of show
To: Daniel Fischer <[email protected]>
Cc: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 10/26/2011 03:29 PM, Daniel Fischer wrote:
> On Wednesday 26 October 2011, 16:23:20, Hugo Ferreira wrote:
>> Hello,
>>
>> Apologies for this newbie question.
>> I have a test function:
>>
>> testLearnRules train = do
>> h<- IO.openFile train IO.ReadMode
>> c<- IO.hGetContents h
>> let proposedRules = instRules $ words c
>> let rs = take 10 $ M.assocs proposedRules
>> let _ = show rs
>> -- let _ = length rs
>> return ()
>>
>> I realize that nothing is executed due to Haskell's
>> lazy evaluation. How can I force show to print
>> something to the screen?
>
> You can't force show to rpint something, since show is a pure function not
> involving IO.
> However, testLearnRules does involve IO, so instead of
>
> let _ = show rs
>
> you could simply print it out,
>
> print rs
>
> -- equivalently, putStrLn (show rs)
>
Thank you,
Hugo F.
>>
>> Appreciate any pointers,
>>
>> TIA,
>> Hugo F.
>
------------------------------
Message: 6
Date: Wed, 26 Oct 2011 19:01:40 +0100
From: Stephen Tetley <[email protected]>
Subject: Re: [Haskell-beginners] Generating Code To Embed in an Event
Loop
Cc: [email protected]
Message-ID:
<cab2tpraq3+mnznmjbxa0ogz6ihw94zbuppcdtowsg0y3bq-...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Hi Darrin
I'd contend code generation isn't particularly hard or even tedious,
but there are two big problems. One, its inflexible - its almost
always easier to change code in the target language than a generator.
Two, in essence a generator already contains the target program plus
the scaffolding to generate it. If you don't have many variations to
generate it is more work (often much more work) to make a generator
rather than hand code the target language program.
Best wishes
Stephen
------------------------------
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