Cabal can't open a TCP connection
Simon Peyton Jones
simonpj at microsoft.com
Thu May 8 16:20:16 UTC 2014
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).
From: Kim-Ee Yeoh [mailto:ky3 at atamo.com]
Sent: 08 May 2014 14:48
To: Simon Peyton Jones
Cc: Herbert Valerio Riedel; Simon Marlow; ghc-devs at haskell.org
Subject: Re: Cabal can't open a TCP connection
On Thu, May 8, 2014 at 8:22 PM, Simon Peyton Jones <simonpj at microsoft.com<mailto:simonpj at microsoft.com>> wrote:
On a machine that doesn't need to use a proxy server, what should $http_proxy be set to?
It's a Maybe (Maybe String) problem. Blame Cabal for not ignoring an empty http_proxy. The *nix programs I've tried treat empty as unset.
The solution is: unset HTTP_PROXY.
Från: Simon Peyton Jones<mailto:simonpj at microsoft.com>
Skickat: 2014-05-08 14:04
Till: ghc-devs at haskell.org<mailto:ghc-devs at haskell.org>
Kopia: Simon Marlow<mailto:marlowsd at gmail.com>
Ämne: Cabal can't open a TCP connection
Cabal can’t open a TCP connection from my Linux box. It used to work fine. Here’s what it says:
cabal -v3 update
Downloading the latest package list from hackage.haskell.org
GET http://hackage.haskell.org/packages/archive/00-index.tar.gz HTTP/1.1
proxy uri host: , port:
Creating new connection to
cabal: openTCPConnection: host lookup failure for ""
simonpj at cam-05-unx:~/code/HEAD$ cabal --version
cabal-install version 22.214.171.124
using version 126.96.36.199 of the Cabal library
simonpj at 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.
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