On Tue, Nov 17, 2020 at 06:54:58PM -0500, amindfv--- via Haskell-Cafe wrote:
tl;dr: I seem to have two versions of 'text' on my system, both of which should have an instance for (Binary Text). However, one version seems to claim not to have that instance.
$ /usr/local/bin/ghci -package text-1.2.4.1 test.hs GHCi, version 8.10.2: https://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( test.hs, interpreted )
test.hs:4:16: error: • No instance for (B.Binary T.Text) arising from a use of ‘B.encode’
Hard to say what's different on your system, but on a Fedora 31 system with GHC 8.10.2 and text-1.2.4.1, I'm unable to reproduce the symptoms you report. $ ghci -package text-1.2.4.1 GHCi, version 8.10.2: https://www.haskell.org/ghc/ :? for help Prelude> import qualified Data.Text as T Prelude T> import qualified Data.Binary as B Prelude T B> main = print $ B.encode $ T.pack "hello" Prelude T B> main "\NUL\NUL\NUL\NUL\NUL\NUL\NUL\ENQhello" The interface file for Text 1.2.4.1 has the expected instances: $ ghc-pkg list ~/.local/ghc-8.10/lib/ghc-8.10.2/lib/package.conf.d ... text-1.2.4.1 ... ~/.ghc/x86_64-linux-8.10.2/package.conf.d (no packages) $ ghc --show-iface ~/.local/ghc-8.10/lib/ghc-8.10.2/lib/x86_64-linux-ghc-8.10.2/text-1.2.4.1/Data/Text.hi | grep '^instance' instance [orphan] Data.Binary.Class.Binary [Data.Text.Internal.Text] instance [orphan] Data.Data.Data [Data.Text.Internal.Text] instance [orphan] GHC.Classes.Eq [Data.Text.Internal.Text] instance [orphan] GHC.Exts.IsList [Data.Text.Internal.Text] instance [orphan] Data.String.IsString [Data.Text.Internal.Text] instance [orphan] Language.Haskell.TH.Syntax.Lift [GHC.Types.LiftedRep, instance [orphan] GHC.Base.Monoid [Data.Text.Internal.Text] instance [orphan] Control.DeepSeq.NFData [Data.Text.Internal.Text] instance [orphan] GHC.Classes.Ord [Data.Text.Internal.Text] instance [orphan] Text.Printf.PrintfArg [Data.Text.Internal.Text] instance [orphan] GHC.Read.Read [Data.Text.Internal.Text] instance [orphan] GHC.Base.Semigroup [Data.Text.Internal.Text] -- Viktor.