GHC 9.6.3 support

[maerten]

Hello,
I've just tried compiling servant-multipart with GHC 9.6.3 and am hitting this issue:

servant-multipart-client> build
servant-multipart-client> Preprocessing executable 'server' for servant-multipart-client-0.12.1..
servant-multipart-client> Building executable 'server' for servant-multipart-client-0.12.1..
servant-multipart-client> [1 of 1] Compiling Main
servant-multipart-client> [2 of 2] Linking .stack-work/dist/aarch64-osx/Cabal-3.10.1.0/build/server/server
servant-multipart-client> ld: warning: ignoring duplicate libraries: '-lm'
servant-multipart-client> Preprocessing library for servant-multipart-client-0.12.1..
servant-multipart-client> Building library for servant-multipart-client-0.12.1..
servant-multipart-client> [1 of 1] Compiling Servant.Multipart.Client
servant-multipart-client>
servant-multipart-client> /private/var/folders/0c/zmpjp7l568xcvnt49pkkn5p00000gn/T/stack-29e507a3bc44f1b9/servant-multipart-client-0.12.1/src/Servant/Multipart/Client.hs:77:18: error: [GHC-39999]
servant-multipart-client>     • Ambiguous type variable ‘f1’ arising from a use of ‘source’
servant-multipart-client>       prevents the constraint ‘(Foldable f1)’ from being solved.
servant-multipart-client>       Probable fix: use a type annotation to specify what ‘f1’ should be.
servant-multipart-client>       Potentially matching instances:
servant-multipart-client>         instance Foldable (Either a) -- Defined in ‘Data.Foldable’
servant-multipart-client>         instance Foldable Proxy -- Defined in ‘Data.Foldable’
servant-multipart-client>         ...plus 7 others
servant-multipart-client>         ...plus 93 instances involving out-of-scope types
servant-multipart-client>         (use -fprint-potential-instances to see them all)
servant-multipart-client>     • In the first argument of ‘(.)’, namely ‘source’
servant-multipart-client>       In the expression: source . pure
servant-multipart-client>       In an equation for ‘loadFile’: loadFile _ = source . pure
servant-multipart-client>    |
servant-multipart-client> 77 |     loadFile _ = source . pure
servant-multipart-client>    |                  ^^^^^^
servant-multipart-client>
servant-multipart-client> /private/var/folders/0c/zmpjp7l568xcvnt49pkkn5p00000gn/T/stack-29e507a3bc44f1b9/servant-multipart-client-0.12.1/src/Servant/Multipart/Client.hs:77:27: error: [GHC-39999]
servant-multipart-client>     • Ambiguous type variable ‘f1’ arising from a use of ‘pure’
servant-multipart-client>       prevents the constraint ‘(Applicative f1)’ from being solved.
servant-multipart-client>       Probable fix: use a type annotation to specify what ‘f1’ should be.
servant-multipart-client>       Potentially matching instances:
servant-multipart-client>         instance Applicative (Either e) -- Defined in ‘Data.Either’
servant-multipart-client>         instance Applicative Proxy -- Defined in ‘Data.Proxy’
servant-multipart-client>         ...plus 8 others
servant-multipart-client>         ...plus 75 instances involving out-of-scope types
servant-multipart-client>         (use -fprint-potential-instances to see them all)
servant-multipart-client>     • In the second argument of ‘(.)’, namely ‘pure’
servant-multipart-client>       In the expression: source . pure
servant-multipart-client>       In an equation for ‘loadFile’: loadFile _ = source . pure
servant-multipart-client>    |
servant-multipart-client> 77 |     loadFile _ = source . pure
servant-multipart-client>    |                           ^^^^
servant-multipart-client>
servant-multipart-client> /private/var/folders/0c/zmpjp7l568xcvnt49pkkn5p00000gn/T/stack-29e507a3bc44f1b9/servant-multipart-client-0.12.1/src/Servant/Multipart/Client.hs:135:37: error: [GHC-39999]
servant-multipart-client>     • Could not deduce ‘Foldable f0’ arising from a use of ‘source’
servant-multipart-client>       from the context: MultipartClient tag
servant-multipart-client>         bound by the type signature for:
servant-multipart-client>                    multipartToBody :: forall tag.
servant-multipart-client>                                       MultipartClient tag =>
servant-multipart-client>                                       LBS.ByteString -> MultipartData tag -> RequestBody
servant-multipart-client>         at src/Servant/Multipart/Client.hs:(111,1)-(115,30)
servant-multipart-client>       The type variable ‘f0’ is ambiguous
servant-multipart-client>       Potentially matching instances:
servant-multipart-client>         instance Foldable (Either a) -- Defined in ‘Data.Foldable’
servant-multipart-client>         instance Foldable Proxy -- Defined in ‘Data.Foldable’
servant-multipart-client>         ...plus 7 others
servant-multipart-client>         ...plus 93 instances involving out-of-scope types
servant-multipart-client>         (use -fprint-potential-instances to see them all)
servant-multipart-client>     • In the first argument of ‘(.)’, namely ‘source’
servant-multipart-client>       In the first argument of ‘($)’, namely
servant-multipart-client>         ‘source . pure . lencode . iValue’
servant-multipart-client>       In the fourth argument of ‘renderPart’, namely
servant-multipart-client>         ‘(source . pure . lencode . iValue $ input)’
servant-multipart-client>     |
servant-multipart-client> 135 |                                    (source . pure . lencode . iValue $ input)
servant-multipart-client>     |                                     ^^^^^^
servant-multipart-client>
servant-multipart-client> /private/var/folders/0c/zmpjp7l568xcvnt49pkkn5p00000gn/T/stack-29e507a3bc44f1b9/servant-multipart-client-0.12.1/src/Servant/Multipart/Client.hs:135:46: error: [GHC-39999]
servant-multipart-client>     • Could not deduce ‘Applicative f0’ arising from a use of ‘pure’
servant-multipart-client>       from the context: MultipartClient tag
servant-multipart-client>         bound by the type signature for:
servant-multipart-client>                    multipartToBody :: forall tag.
servant-multipart-client>                                       MultipartClient tag =>
servant-multipart-client>                                       LBS.ByteString -> MultipartData tag -> RequestBody
servant-multipart-client>         at src/Servant/Multipart/Client.hs:(111,1)-(115,30)
servant-multipart-client>       The type variable ‘f0’ is ambiguous
servant-multipart-client>       Potentially matching instances:
servant-multipart-client>         instance Applicative (Either e) -- Defined in ‘Data.Either’
servant-multipart-client>         instance Applicative Proxy -- Defined in ‘Data.Proxy’
servant-multipart-client>         ...plus 8 others
servant-multipart-client>         ...plus 75 instances involving out-of-scope types
servant-multipart-client>         (use -fprint-potential-instances to see them all)
servant-multipart-client>     • In the first argument of ‘(.)’, namely ‘pure’
servant-multipart-client>       In the second argument of ‘(.)’, namely ‘pure . lencode . iValue’
servant-multipart-client>       In the first argument of ‘($)’, namely
servant-multipart-client>         ‘source . pure . lencode . iValue’
servant-multipart-client>     |
servant-multipart-client> 135 |                                    (source . pure . lencode . iValue $ input)
servant-multipart-client>     |                                              ^^^^

[ysangkok]

Could you please dump your whole dep graph? You can use a tool such as cabal-plan. Probably some dependency is getting pinned to a lower version.

This looks related to:

• [servant] Generalize type of Servant.Types.SourceT.source to any foldable servant#1593

This works for me:

cabal repl -w ghc-9.6.2 -b servant-multipart-client -c 'servant==0.20.1'

with the index-state of today.

[ysangkok]

Oh, I see you're using 0.12.1. You should try out version 0.12.2.

[ysangkok]

@erlandsona here is version 0.12.2: https://hackage.haskell.org/package/servant-multipart-client

I can review your patch if you send it.

[erlandsona]

Hey sorry I realized the function got moved to servant-multipart-client 😅