| my best guess: your proxy settings seem off I think that's a good guess. On this machine we used to have to use a proxy (so $http_proxy had a URL in it), but now we don't (so $http_proxy is empty). Maybe that's confusing Cabal. On a machine that doesn't need to use a proxy server, what should $http_proxy be set to? Simon | -----Original Message----- | From: Herbert Valerio Riedel [mailto:hvriedel@gmail.com] | Sent: 08 May 2014 13:41 | To: Simon Peyton Jones | Cc: ghc-devs@haskell.org; Simon Marlow | Subject: Re: Cabal can't open a TCP connection | | On 2014-05-08 at 14:03:22 +0200, Simon Peyton Jones wrote: | > Dear ghc-devs | > Cabal can't open a TCP connection from my Linux box. It used to work | fine. Here's what it says: | | [...] | | > proxy uri host: , port: | > Creating new connection to | > cabal: openTCPConnection: host lookup failure for "" | | my best guess: your proxy settings seem off

Spot on, Kim-Ee. Thanks. unsetting http_proxy fixed it. I’m fwding to cabal-devel: it would be great that if “http_proxy” was set to “”, then it behaved just as if it was un-set. The current behaviour is very confusing (to me anyway). Simon From: Kim-Ee Yeoh [mailto:ky3@atamo.com] Sent: 08 May 2014 14:48 To: Simon Peyton Jones Cc: Herbert Valerio Riedel; Simon Marlow; ghc-devs@haskell.org Subject: Re: Cabal can't open a TCP connection On Thu, May 8, 2014 at 8:22 PM, Simon Peyton Jones mailto:simonpj@microsoft.com> wrote: On a machine that doesn't need to use a proxy server, what should $http_proxy be set to? It's a Maybe (Maybe String) problem. Blame Cabal for not ignoring an empty http_proxy. The *nix programs I've tried treat empty as unset. The solution is: unset HTTP_PROXY. -- Kim-Ee ________________________________ Från: Simon Peyton Jonesmailto:simonpj@microsoft.com Skickat: ‎2014-‎05-‎08 14:04 Till: ghc-devs@haskell.orgmailto:ghc-devs@haskell.org Kopia: Simon Marlowmailto:marlowsd@gmail.com Ämne: Cabal can't open a TCP connection Dear ghc-devs Cabal can’t open a TCP connection from my Linux box. It used to work fine. Here’s what it says: cabal -v3 update Downloading the latest package list from hackage.haskell.org Sending: GET http://hackage.haskell.org/packages/archive/00-index.tar.gz HTTP/1.1 User-Agent: cabal-install/1.16.0.2 Host: hackage.haskell.org proxy uri host: , port: Creating new connection to cabal: openTCPConnection: host lookup failure for "" simonpj@cam-05-unx:~/code/HEAD$ cabal --version cabal-install version 1.16.0.2 using version 1.16.0.3 of the Cabal library simonpj@cam-05-unx:~/code/HEAD$ Can anyone help me work out what to do? git works just fine, so the internet is connected all right. Thanks Simon