As for an example. Clone this repository

https://github.com/sras/servant-examples

Then cd into it and run

cat servant-examples.cabal | guix import hackage -s -r

The '-s' option reads from stdin, the '-r' option imports everything 
recursively.

It throws this output:

Starting download of /tmp/guix-file.TykbjO
 From 
https://hackage.haskell.org/package/servant-examples/servant-examples-0.1.0.0.tar.gz...
download failed 
"https://hackage.haskell.org/package/servant-examples/servant-examples-0.1.0.0.tar.gz" 
404 "Not Found"

Starting download of /tmp/guix-file.TykbjO
 From 
https://web.archive.org/web/20230307175126/https://hackage.haskell.org/package/servant-examples/servant-examples-0.1.0.0.tar.gz...
download failed 
"https://web.archive.org/web/20230307175126/https://hackage.haskell.org/package/servant-examples/servant-examples-0.1.0.0.tar.gz" 
404 "NOT FOUND"
Trying to use Disarchive to assemble /tmp/guix-file.TykbjO...
could not find its Disarchive specification
failed to download "/tmp/guix-file.TykbjO" from 
"https://hackage.haskell.org/package/servant-examples/servant-examples-0.1.0.0.tar.gz"
Syntax error: unexpected end of input
Syntax error: unexpected end of input
(define-public ghc-servant-examples
   (package
     (name "ghc-servant-examples")
     (version "0.1.0.0")
     (source (origin
               (method url-fetch)
               (uri (hackage-uri "servant-examples" version))
               (sha256
                (base32
                 "failed to download tar archive"))))
     (build-system haskell-build-system)
     (properties '((upstream-name . "servant-examples")))
     (inputs (list ghc-servant
                   ghc-servant-server
                   ghc-servant-swagger
                   ghc-swagger2
                   ghc-wai
                   ghc-aeson
                   ghc-warp))
     (home-page "https://github.com/githubuser/servant-examples#readme")
     (synopsis "")
     (description "")
     (license license:bsd-3)))


My guess the "Syntax error" is from the missing "ghc-servant-swagger" 
package.

Also, the source should be changed to (local-file "./" #:recursive? #t) 
but I guess the stdin option can't guess that. I guess one should add an 
'-f' option to read the .cabal file.

Anyways, it seems the "-r" option doesn't work here. I was expecting 
"ghc-servant-swagger" to be defined as well.

P.

On 7.03.2023 17:02, Ludovic Courtès wrote:
> Hi,
> 
> Przemysław Kamiński <cgenie@pm.me> skribis:
> 
>> 3. I run `guix build -L <my-custom-guix-package-dir> -m manifest.scm
>> (manifest only contains a reference to ghc-stuff.scm)
>> 4. I get an error which looks like this:
>> View build log at
>> '/var/log/guix/drvs/j2/wa3vw49l78m85z74x91sklqxwhx87y-ghc-hwodr-0.1.0.drv.bz2'
>>
>> so I fire up
>>
>> bunzip --stdout
>> '/var/log/guix/drvs/j2/wa3vw49l78m85z74x91sklqxwhx87y-ghc-hwodr-0.1.0.drv.bz2'
>>
>> and see that I am missing some Haskell packages.
> 
> Note that the build log should be just above the “View build log” line
> if you scroll up a little bit.  :-)
> 
> Otherwise, like Simon said, I’d recommend getting package definitions by
> running ‘guix import hackage -r’, assuming said packages are on Hackage.
> That should simplify things.
> 
> HTH,
> Ludo’.