Linker change in GHC 7.8 leads to widespread issues

Miëtek Bak mietek at
Wed Dec 3 18:53:22 UTC 2014

I agree, and I’m hoping to help improve these matters with my project, Halcyon (

Halcyon allows all build-time and run-time dependencies of an application to be explicitly declared and installed with a single invocation.  This builds on the great work done recently in Cabal to get us `cabal freeze`, and works around many long-standing Cabal issues, such as the inability to automatically install missing build-tools.

Halcyon can also be used to restore entire Haskell installations in seconds, and supports GHC versions including 7.8.3, 7.8.2, 7.6.3, 7.6.1, 7.4.2, 7.2.2, and 7.0.4.  Hopefully, being able to swap GHC versions in and out, without needing to have them on disk, should help lessen the amount of work needed for comprehensive testing.

I am currently putting the final touches on my project before announcement.  Please let me know what you think.


On 2014-12-03, at 18:25, Howard B. Golden <howard_b_golden at> wrote:

> Hi,
> There aren't more complaints because most people haven't tried 7.8 seriously yet. (I didn't notice the problem since I've only been using GHC 7.8 under Windows.) This points out the need for some sort of regular testing of canaries (full systems producing known results) to test the entire toolchain including common libraries (HP, perhaps) and Cabal.
> At the risk of antagonizing the developers again, I will point out that there is a bit of disconnect between GHC developers, Cabal developers, library developers and users (application developers). Without slowing the GHC developers' creativity, there is a need to look at the experience of the application developers. FWIW, my sense is that there is too much turbulence for many potential application developers to adopt Haskell as their production platform unless they have significant in-house resources to deal with the rapid changes. (As as thought experiment, how many changes have to be made to Real World Haskell's programs to get them to run?)
> Howard
> ----- Original Message -----
> From: Simon Marlow <marlowsd at>
> To: Miëtek Bak <mietek at>; Carter Schonwald <carter.schonwald at>
> Cc: "cabal-devel at" <cabal-devel at>; "ghc-devs at" <ghc-devs at>
> Sent: Wednesday, December 3, 2014 4:03 AM
> Subject: Re: Linker change in GHC 7.8 leads to widespread issues
> I'm actually rather surprised we got away without doing this up to now. 
>  Why haven't there been more complaints?
> Cheers,
> Simon
> _______________________________________________
> ghc-devs mailing list
> ghc-devs at

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