May 2015 - Beginners - Haskell.org

Haskell ghc, linking error when trying to compile a program using ghc and Euterpea
by Florian Gillard 02 May '15

02 May '15

I am checking out the computing music development library Euterpea, and I am trying to compile the following basic program: import Euterpea t251 :: Music Pitch t251 = let dMinor = d 4 wn :=: f 4 wn :=: a 4 wn gMajor = g 4 wn :=: b 4 wn :=: d 5 wn cMajor = c 4 bn :=: e 4 bn :=: g 4 bn in dMinor :+: gMajor :+: cMajor main = play t251 the program works fine inside ghci, but when I try to compile it using ghc test.hs I get the following error message: Linking test ... /usr/bin/ld: /home/fayong/.cabal/lib/PortMidi-0.1.3/ghc-7.6.3/libHSPortMidi-0.1.3.a(ptlinux.o): undefined reference to symbol 'pthread_create@@GLIBC_2.2.5' //lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO missing from command line collect2: error: ld returned 1 exit status It seems to be a linking error but I don't know how to fix it. (I tried to pass -lpthread as an option but it didn't work) I installed Euterpea via cabal, on linux mint 17

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Re: [Haskell-beginners] Loop
by Shishir Srivastava 01 May '15

01 May '15

Hi Marcin, Thanks for your response. Yes my intention to use 'do' was to implement it in so called 'imperative' style coding. So if I understand it correctly there is no other way to achieve it via 'do' w/o using the monad transformers? Thanks again Shishir

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Loop
by Shishir Srivastava 01 May '15

01 May '15

Hi, Please can anyone point out the correct way of doing this - I am simply trying to print "Test" in a loop based on the counter derived from the list - ---- do _ <- [1..4] b <- putStrLn "Test" return b --- The intended output is to print 'Test' 4 times. Clearly there is a mismatch between the Monad types but I can't see how to achieve this without causing the conflict. Thanks, Shishir

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