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!