October 2011 - Beginners

merge two files in to one file
by kolli kolli 05 Oct '11

05 Oct '11

Hi, Can anyone tell me how to merge two files in to one file.

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Peer review of an attempt to solve the golf-tee puzzle?
by Scott Thoman 05 Oct '11

05 Oct '11

Hi, I'm looking to see of anyone is interested in a quick code review. I coded a quick solution to the golf-tee puzzle (like you see a places like Cracker Barrel, 15 piece triangle where you hop the pegs in order to get down to one left). My solution seems to work, seems to perform ok, and seems to come up with a very large number of distinct solutions. I'm looking for some feedback as far as: - am I "getting" it? :) - is the approach general enough? - does it look anything like idiomatic haskell? - any places to make things simpler or more point-free-ish? - any types are overkill, too restrictive (I added the Board type so maybe it could be an instance of Show to display the triangle but didn't go that far) I'll attach the three files here. Thanks in advance for any feedback... /stt

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Re: [Haskell-beginners] [aklug] Re: VPS
by Christopher Howard 04 Oct '11

04 Oct '11

On 10/04/2011 08:36 AM, adam bultman wrote: > What, do I have to *give* you one or something? Because I can, y'know. > > Just so long as you don't spam :) > > On 10/03/2011 06:59 PM, Christopher Howard wrote: >> On 10/03/2011 02:28 PM, adam bultman wrote: >>> Choward, any chance you have a legitimate email somewhere else you could >>> relay through, authenticated-style? >>> >> Legitimate!? My server is legitimate!!! >> >> Assuming you mean a gmail account or such... no. >> >>> You'd accept mail on your dynamic IP, but any outgoing mail sent via >>> your server would be relayed through a third party, via your username >>> and password. It's pretty easy to set up in Postfix, anyway, even with >>> TLS to boot. >>> > heh, heh... thanks, but I actually like the VPS idea better, as I was thinking about getting a cheap one to play around with anyway. Even the cheapest one comes with a static IP, so I could just receive the mail there and forward it on to my personal server, or something like that. As a point of curiosity: with your suggestion, do you rewrite the sender field, or do you send and receive e-mails with different addresses? It seems like a few years ago I remember trying to use a server belonging to one domain to send mail from another domain, and some of the mail was bounced back because the receiving servers detected that the domain in the sender field did not match that of the sending server. @Bruce: Thanks also for the offer, but I think I'll try out a VPS solution. -- frigidcode.com theologia.indicium.us

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LZMA for Haskell?
by Paulo Pocinho 04 Oct '11

04 Oct '11

Hello list. I'd like to use LZMA to create/extract archives and compare CRC from archived files. What do I need to use LZMA in Haskell? There is a page called "Library/Compression" in the wiki [1] but it is from 2005, using LZMA version 4.06. Besides being old, I can only find the LZMA SDK version 9.20 for download. The only related package I can find on hackage is lzma-enumerator [2]. Trying to install with cabal requires an old header named lzma.h that is no longer available. [1] http://www.haskell.org/haskellwiki/Library/Compression [2] http://hackage.haskell.org/package/lzma-enumerator

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How to write replicateM with interspersed guards?
by Sebastien Zany 04 Oct '11

04 Oct '11

What would be the idiomatic way to write a function which expands to the following? f n m = do { x1 <- m; guard (f [x1]); x2 <- m; guard (f [x1, x2]); . . . xn <- m; guard (f [x1,x2,...,xn]); } What I'm trying to do is generate a list of lists of length n with some property (checked by f) efficiently.

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A post about Currying and Partial application
by Petar Radosevic 04 Oct '11

04 Oct '11

Hi, Like most here I'm also learning the beautiful language called Haskell and arrived at the subject of Currying. To see if I really understood the concept, I decided to write a blog post about it. http://s3.wunki.org/posts/2011-09-30-curry-and-its-partial-application.html I hope it helps some of the beginners here. Please take a look at it and let me know if I'm wrong or if I missed something. Thank you! -- Petar Radošević, Programmer wunki.org | @wunki

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Re: [Haskell-beginners] How to write replicateM with interspersedguards?
by anyzhen 04 Oct '11

04 Oct '11

like this? let inits' xs = drop 1 $ inits xs in let getLists n m = inits' take n (repeat m) in f m n =map (\x-> guard $ f x) xs where xs =getLists n m ------------------ Original ------------------ From: "Sebastien Zany"; Date: 2011年10月4日(星期二) 晚上8:27 To: "Haskell Beginners"; Subject: [Haskell-beginners] How to write replicateM with interspersedguards? What would be the idiomatic way to write a function which expands to the following? f n m = do { x1 <- m; guard (f [x1]); x2 <- m; guard (f [x1, x2]); . . . xn <- m; guard (f [x1,x2,...,xn]); } What I'm trying to do is generate a list of lists of length n with some property (checked by f) efficiently.

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Trying out GuiTV
by Martin Baldan 02 Oct '11

02 Oct '11

Hello all, I hope this is the right place to ask :) I'm very new to Haskell, but I'm intrigued with the concept of "tangible values". I'm trying to run the examples from Conal Elliott's TV library. I did Cabal install TV and GuiTV. Then I tried to compile the examples from the GuiTV package, but no luck, so I decided to go for something simpler, so I took the examples from the TV site http://haskell.org/haskellwiki/TV but I used the imports from the GuiTV package. I called the file "myexample.hs" and it looks like this: ------------------ {-# LANGUAGE OverlappingInstances, UndecidableInstances , IncoherentInstances, FlexibleContexts , TypeSynonymInstances, FlexibleInstances , MultiParamTypeClasses #-} -- For ghc 6.6 compatibility {-# OPTIONS -fglasgow-exts -fallow-overlapping-instances -fallow-incoherent-instances #-} ---- Some GuiTV examples. See also the examples in TV. import Data.List (sort) -- my addition import Data.Monoid -- end my addition import Interface.TV.UI import Control.Arrow.DeepArrow import Data.FunArr -- TypeCompose import Data.Title -- To pick up the FunArr instance for OFun. import Interface.TV.OFun() reverseT :: CTV (String -> String) reverseT = tv (oTitle "reverse" defaultOut) reverse main = runUI reverseT ----------------------- I don't understand the "#LANGUAGE" and "#OPTIONS" parts, I just left them as they were. I assume that they don't influence the result, since they are comments. I also added the "import Data.Monoid" line, because of a previous error message. I guess it doesn't hurt. Then I type "ghc ./myexample.hs" and the output is: ------------------ myexample.o: In function `s2oa_info': (.text+0x2b): undefined reference to `TVzm0zi4zi7_InterfaceziTVziDefaults_zdfDefaultOutsrcsnkZMZN0_closure' myexample.o: In function `s2ob_info': (.text+0x61): undefined reference to `TVzm0zi4zi7_InterfaceziTVziDefaults_zdfDefaultInsrcZMZN0_closure' myexample.o: In function `s2od_info': (.text+0xc6): undefined reference to `TVzm0zi4zi7_InterfaceziTVziDefaults_zdfDefaultOutsrcsnkZLzmzgZR_closure' myexample.o: In function `s2of_info': (.text+0x169): undefined reference to `TVzm0zi4zi7_InterfaceziTVziOutput_oTitle_closure' myexample.o: In function `r1jF_info': (.text+0x1b7): undefined reference to `TVzm0zi4zi7_InterfaceziTVziTangible_tv_closure' myexample.o: In function `r2nX_info': (.text+0x224): undefined reference to `GuiTVzm0zi4_InterfaceziTVziUI_zdfCommonOutsZCzi_closure' myexample.o: In function `r2nX_info': (.text+0x22b): undefined reference to `GuiTVzm0zi4_InterfaceziTVziUI_zdfCommonInsZCzi_closure' myexample.o: In function `r2nX_info': (.text+0x28a): undefined reference to `GuiTVzm0zi4_InterfaceziTVziUI_runUI_closure' myexample.o: In function `r2nX_info': (.text+0x325): undefined reference to `__stginit_GuiTVzm0zi4_InterfaceziTVziUI_' myexample.o: In function `r2nX_info': (.text+0x32f): undefined reference to `__stginit_TVzm0zi4zi7_InterfaceziTVziOFun_' myexample.o: In function `r2nX_info': (.text+0x339): undefined reference to `__stginit_DeepArrowzm0zi3zi3_ControlziArrowziDeepArrow_' myexample.o: In function `r2nX_info': (.text+0x343): undefined reference to `__stginit_DeepArrowzm0zi3zi3_DataziFunArr_' myexample.o: In function `r2nX_info': (.text+0x34d): undefined reference to `__stginit_TypeComposezm0zi8zi3_DataziTitle_' myexample.o: In function `s2oc_info': (.text+0x7c): undefined reference to `TVzm0zi4zi7_InterfaceziTVziDefaults_defaultOut_info' myexample.o: In function `r1jF_srt': (.data+0x8): undefined reference to `TVzm0zi4zi7_InterfaceziTVziOutput_oTitle_closure' myexample.o: In function `r1jF_srt': (.data+0xc): undefined reference to `TVzm0zi4zi7_InterfaceziTVziTangible_tv_closure' myexample.o: In function `r1jF_srt': (.data+0x10): undefined reference to `TVzm0zi4zi7_InterfaceziTVziDefaults_zdfDefaultOutsrcsnkZMZN0_closure' myexample.o: In function `r1jF_srt': (.data+0x14): undefined reference to `TVzm0zi4zi7_InterfaceziTVziDefaults_zdfDefaultOutsrcsnkZLzmzgZR_closure' myexample.o: In function `r1jF_srt': (.data+0x18): undefined reference to `TVzm0zi4zi7_InterfaceziTVziDefaults_zdfDefaultInsrcZMZN0_closure' myexample.o: In function `r2nX_srt': (.data+0x24): undefined reference to `GuiTVzm0zi4_InterfaceziTVziUI_zdfCommonOutsZCzi_closure' myexample.o: In function `r2nX_srt': (.data+0x28): undefined reference to `GuiTVzm0zi4_InterfaceziTVziUI_zdfCommonInsZCzi_closure' myexample.o: In function `r2nX_closure': (.data+0x40): undefined reference to `GuiTVzm0zi4_InterfaceziTVziUI_runUI_closure' collect2: ld returned 1 exit status ------------------ I have no clue what the problem may be. Any ideas? Thanks in advance!

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