Problem Installing ad (Automatic Differentiation) Package

Edward Kmett ekmett at
Sat Apr 21 21:33:20 CEST 2012

I'll need to get an older ghc version installed, so I can try to figure out what changes are needed to make template haskell bits compatible back to the current platform. 'ad' uses TH rather extensively, and sadly, the update to support ghc 7.4.1 broke a fair bit of the old code gen -- as I recall, it is a rather lage amount of code that got changed, so I may not get a platform compatible version of ad released before the new platform renders the need less pressing.

Sent from my iPad

On Apr 21, 2012, at 11:13 AM, Dominic Steinitz <idontgetoutmuch at> wrote:

> Hi,
> I was trying to install ad (Automatic Differentiation) but got the following error. I guess the answer is to upgrade my ghc (perhaps someone could confirm) but I am using the Haskell Platform and would rather stick with that. I see from that the next release is due out in May. Will that be early May? in which case I may well wait a week or will it be late May? in which case I might bite the bullet and upgrade my ghc.
> Thanks, Dominic
> Building template-haskell-
> [1 of 7] Compiling Language.Haskell.TH.Syntax.Internals ( Language/Haskell/TH/Syntax/Internals.hs, dist/build/Language/Haskell/TH/Syntax/Internals.o )
> [2 of 7] Compiling Language.Haskell.TH.Syntax ( Language/Haskell/TH/Syntax.hs, dist/build/Language/Haskell/TH/Syntax.o )
> [3 of 7] Compiling Language.Haskell.TH.PprLib ( Language/Haskell/TH/PprLib.hs, dist/build/Language/Haskell/TH/PprLib.o )
> Language/Haskell/TH/PprLib.hs:55:10:
>    Illegal instance declaration for `Show Doc'
>      (All instance types must be of the form (T t1 ... tn)
>       where T is not a synonym.
>       Use -XTypeSynonymInstances if you want to disable this.)
>    In the instance declaration for `Show Doc'
> Updating documentation index /Users/Test/Library/Haskell/doc/index.html
> cabal: Error: some packages failed to install:
> ad- depends on template-haskell- which failed to install.
> template-haskell- failed during the building phase. The exception was:
> ExitFailure 1
> The Glorious Glasgow Haskell Compilation System, version 7.0.3
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