March 2014 - Beginners

Build setup with dynamic linkining
by harry 04 Mar '14

04 Mar '14

I've removed the static libraries from a machine to save space, and configured cabal to build both libraries and executables dynamically. This works for everything except packages with Custom build-type (e.g. Happy), when cabal-install will try to build setup against the non-existent static libraries. Is there any way to force cabal to build dist/setup dynamically?

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"Developing Web Applications with Haskell and Yesod"
by KMandPJLynch 03 Mar '14

03 Mar '14

I'm reading the O'Reilly book "Developing Web Applications with Haskell and Yesod" but can't get the helloworld.hs app, from the book, to work. This is what I did: 1. I downloaded Haskell and it works just fine. 2. cabal update 3. cabal install yesod 4. I downloaded the helloworld.hs program - see following: {-# LANGUAGE TypeFamilies, QuasiQuotes, MultiParamTypeClasses, TemplateHaskell, OverloadedStrings #-} import Yesod data HelloWorld = HelloWorld mkYesod "HelloWorld" [parseRoutes] / HomeR Get|] instance Yesod HelloWorld getHomeR :: Handler RepHtml getHomeR = defaultLayout [whamlet[|Hell World!|] main :: IO () main = warpDebug 3000 HelloWorld 5. I went to the terminal on a Mac and entered command: runhaskell helloworld.hs 6. on the terminal the following is displayed: Hell World! 7. I opened a Safari browser and entered: http://localhost:3000 8. the following error message is displayed: "Safari can't connect to Server. Safari can't open the page http://localhost:3000/ because Safari can't connect to localhost" I'd appreciate any help.

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Re: [Haskell-beginners] list problem
by Tyler Huffman 03 Mar '14

03 Mar '14

I would definitely recommend the #haskell IRC channel for simple questions as well. Usually they're better at less complicated questions than the Haskell Beginner mailing list. Here's a link for some more information: ( http://www.haskell.org/haskellwiki/IRC_channel) Best of luck! On Mon, Mar 3, 2014 at 10:40 AM, Emanuel Koczwara <poczta(a)emanuelkoczwara.pl > wrote: > Hi, > > W dniu 03.03.2014 18:04, Roelof Wobben pisze: > > I am studing this by following the wiki tutorial and then the Haskell > basic tutorial. > But if you have a better tutorial I'm happy to study this one too. > > Roelof > > > > Benjamin Edwards schreef op 3-3-2014 17:59: > > The problem is that you don't seem to understand how singly linked lists > work. I would recommend studying this first, then understanding how to > append a value to the end of the list in haskell will probably make a lot > more sense. > > >> > > This is of course mailing list for beginners and we are happy to help > you, but your questions are _very_ basic. Please take a look at > http://learnyouahaskell.com. > > Regards, > Emanuel > > > _______________________________________________ > Beginners mailing list > Beginners(a)haskell.org > http://www.haskell.org/mailman/listinfo/beginners > > Regards, Tyler Huffman

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list problem
by Roelof Wobben 03 Mar '14

03 Mar '14

Hello, I have this : cons8 n l = n : l x = cons8 8 [1,2,3] main = print x This will be the output: [8.1.2.3] Now the problem is how I can take care that the output will be [1,2,3,4,8] I have to change the function for it. I tried switching n and L in the function but that will not work. Or does I have to do x = cons [1,2,3] 8 and make the function like this cons8 l n = l : n Roelof --- Dit e-mailbericht bevat geen virussen en malware omdat avast! Antivirus-bescherming actief is. http://www.avast.com

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foldr problem
by Roelof Wobben 03 Mar '14

03 Mar '14

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Question about Ord for lists and multi-dimensional lists
by Tyler Huffman 03 Mar '14

03 Mar '14

Hi all, I'm having trouble finding resources explaining how Ord for two lists works. I've created a public gist to explain what I mean. https://gist.github.com/iduhetonas/9318958 Could anybody shed some light on what I'm seeing? Regards, Tyler Huffman

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where do i get wrong
by Roelof Wobben 02 Mar '14

02 Mar '14

Hello, I try to selfstudy haskell by following the yet another haskell tutorial. Now I have the exercise where I have a string and have to convert it into a list of Booleans based on lower cats letter using map. So i tried this x = "aBCde".islower:[] But I see this error : Not in Scope: 'isLower'. Where do I make my error. Do not give the answer otherwise I do not learn anything from it. Roelof --- Dit e-mailbericht bevat geen virussen en malware omdat avast! Antivirus-bescherming actief is. http://www.avast.com

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