Send Beginners mailing list submissions to
beginners@haskell.org
To subscribe or unsubscribe via the World Wide Web, visit
http://www.haskell.org/mailman/listinfo/beginners
or, via email, send a message with subject or body 'help' to
beginners-requ...@haskell.org
You can reach the person managing the list at
beginners-ow...@haskell.org
When replying, please edit your Subject line so it is more specific
than "Re: Contents of Beginners digest..."
Today's Topics:
1. How is takeWhile implemented? (Carlos J. G. Duarte)
2. Re: How is takeWhile implemented? (illusionoflife)
3. Re: How is takeWhile implemented? (Carlos J. G. Duarte)
4. Re: How is takeWhile implemented? (KC)
----------------------------------------------------------------------
Message: 1
Date: Mon, 09 Jul 2012 18:01:49 +0100
From: "Carlos J. G. Duarte" <carlos.j.g.dua...@gmail.com>
Subject: [Haskell-beginners] How is takeWhile implemented?
To: beginners@haskell.org
Message-ID: <4ffb0e7d.9090...@gmail.com>
Content-Type: text/plain; charset="us-ascii"
An HTML attachment was scrubbed...
URL:
<http://www.haskell.org/pipermail/beginners/attachments/20120709/c11d1019/attachment-0001.htm>
------------------------------
Message: 2
Date: Mon, 09 Jul 2012 21:18:54 +0400
From: illusionoflife <ghostlymail...@gmail.com>
Subject: Re: [Haskell-beginners] How is takeWhile implemented?
To: beginners@haskell.org
Message-ID: <1898327.KjfVtskrWR@miracle>
Content-Type: text/plain; charset="us-ascii"
On Monday, July 09, 2012 18:01:49 Carlos J. G. Duarte wrote:
> underK k (x:xs) = (if x < k then [x] else []) ++ underK k xs
>
> -- from [2] ... how does this work anyway?
> fibs = 0 : 1 : zipWith (+) fibs (tail fibs)
> Which seems to work ok. How is takeWhile stopping at a given point and my
> underK not?
Look. In your implementation `underK' you *always* call itself.
So, actually you implemented filter. takeWhile can be implemented(you can
easily see source
http://www.haskell.org/ghc/docs/latest/html/libraries/base/Data-List.html.
Take notion that takeWhile do not call itself anymore if predicate is false.
> Other question is regarding the "$" and ".". I know the $ has lower priority
> and . has more, but is there any more difference that matters, I mean, can
> I always use the "$" everywhere. For example, this main also works: main =
> putStrLn $ show $ sum $ filter even $ takeWhile (<_M) fibs
> Is it doing the same thing?
It only affect amount of parensisis. Point is nice for high-order function
magic.
--
Best regards, illusionoflife.
This mail is for mailing lists.
For private, responce-warrantied
mail use illusion.of.lif...@gmail.com.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 836 bytes
Desc: This is a digitally signed message part.
URL:
<http://www.haskell.org/pipermail/beginners/attachments/20120709/dea3ffd8/attachment-0001.pgp>
------------------------------
Message: 3
Date: Mon, 09 Jul 2012 21:30:40 +0100
From: "Carlos J. G. Duarte" <carlos.j.g.dua...@gmail.com>
Subject: Re: [Haskell-beginners] How is takeWhile implemented?
To: beginners@haskell.org
Message-ID: <4ffb3f70.7070...@gmail.com>
Content-Type: text/plain; charset="us-ascii"
An HTML attachment was scrubbed...
URL:
<http://www.haskell.org/pipermail/beginners/attachments/20120709/a0ec6461/attachment-0001.htm>
------------------------------
Message: 4
Date: Mon, 9 Jul 2012 14:26:44 -0700
From: KC <kc1...@gmail.com>
Subject: Re: [Haskell-beginners] How is takeWhile implemented?
To: "Carlos J. G. Duarte" <carlos.j.g.dua...@gmail.com>,
beginners@haskell.org
Message-ID:
<CAMLKXy=PypLQ_AFRU1cFSU98ro1Yt0LAvanm=pzyq0yhl17...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Then think of another approach to doing the problem. :)
On Mon, Jul 9, 2012 at 1:30 PM, Carlos J. G. Duarte <
carlos.j.g.dua...@gmail.com> wrote:
>
> Thanks, that's it. I had just to move the underK call inside the if:
>
> underK k (x:xs) = if x < k then x : underK k xs else []
>
> ... I'm finding this to be a little too awkward to me!
>
>
>
--
--
Regards,
KC
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://www.haskell.org/pipermail/beginners/attachments/20120709/e580581b/attachment-0001.htm>
------------------------------
_______________________________________________
Beginners mailing list
Beginners@haskell.org
http://www.haskell.org/mailman/listinfo/beginners
End of Beginners Digest, Vol 49, Issue 10
*****************************************
