*** setup configure setup/setup configure --ghc --user --prefix=/usr/local/tmp/archive/install --haddock-option=--use-contents=/package/hslogger-1.0.4 --verbose Configuring hslogger-1.0.4... Flags chosen: small_base=True Warning: No 'build-type' specified. If you do not need a custom Setup.hs or ./configure script then use 'build-type: Simple'. Dependency base >=3: using base-4.2.0.0 Dependency containers -any: using containers-0.3.0.0 Dependency directory -any: using directory-1.0.1.0 Dependency mtl -any: using mtl-1.1.0.2 Dependency network -any: using network-2.2.1.7 Dependency process -any: using process-1.0.1.2 Dependency unix -any: using unix-2.4.0.0 Using Cabal-1.8.0.2 compiled by ghc-6.12 Using compiler: ghc-6.12.1 Using install prefix: /usr/local/tmp/archive/install Binaries installed in: /usr/local/tmp/archive/install/bin Libraries installed in: /usr/local/tmp/archive/install/lib/hslogger-1.0.4/ghc-6.12.1 Private binaries installed in: /usr/local/tmp/archive/install/libexec Data files installed in: /usr/local/tmp/archive/install/share/hslogger-1.0.4 Documentation installed in: /usr/local/tmp/archive/install/share/doc/hslogger-1.0.4 Using alex version 2.3.1 found on system at: /usr/bin/alex Using ar found on system at: /usr/bin/ar Using c2hs version 0.16.0 found on system at: /usr/local/bin/c2hs Using cpphs version 1.11 found on system at: /usr/local/bin/cpphs Using ffihugs found on system at: /usr/local/bin/ffihugs Using gcc version 4.4.3 found on system at: /usr/bin/gcc Using ghc version 6.12.1 found on system at: /usr/local/bin/ghc Using ghc-pkg version 6.12.1 found on system at: /usr/local/bin/ghc-pkg Using greencard found on system at: /usr/local/tmp/archive/install/bin/greencard Using haddock version 2.7.2 found on system at: /usr/local/bin/haddock Using happy version 1.17 found on system at: /usr/local/bin/happy No hmake found Using hsc2hs version 0.67 found on system at: /usr/local/bin/hsc2hs Using hscolour version 1.16 found on system at: /usr/local/bin/HsColour Using hugs found on system at: /usr/local/bin/hugs No jhc found Using ld found on system at: /usr/bin/ld No lhc found No lhc-pkg found No nhc98 found Using pkg-config version 0.22 found on system at: /usr/bin/pkg-config Using ranlib found on system at: /usr/bin/ranlib Using strip found on system at: /usr/bin/strip Using tar found on system at: /bin/tar *** setup haddock setup/setup haddock --verbose --html-location=/packages/archive/$pkg/$version/doc/html --hyperlink-source Running Haddock for hslogger-1.0.4... /usr/local/bin/haddock --use-contents=/package/hslogger-1.0.4 --ghc-version Creating dist/build (and its parents) Creating dist/build/autogen (and its parents) Preprocessing library hslogger-1.0.4... Preprocessing executables for hslogger-1.0.4... Running hscolour for hslogger-1.0.4... Creating dist/doc/html/hslogger (and its parents) Creating dist/doc/html/hslogger/src (and its parents) /usr/local/bin/HsColour -print-css -odist/doc/html/hslogger/src/hscolour.css /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log.html src/System/Log.hs /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log-Handler.html src/System/Log/Handler.hs /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log-Handler-Simple.html src/System/Log/Handler/Simple.hs /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log-Handler-Syslog.html src/System/Log/Handler/Syslog.hs /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log-Handler-Growl.html src/System/Log/Handler/Growl.hs /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log-Logger.html src/System/Log/Logger.hs Warning: The documentation for the following packages are not installed. No links will be generated to these packages: ffi-1.0, rts-1.0 /usr/local/bin/ghc --print-libdir /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28646/src/System/Log.hs src/System/Log.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28646/src/System/Log/Handler.hs src/System/Log/Handler.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28646/src/System/Log/Handler/Simple.hs src/System/Log/Handler/Simple.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28646/src/System/Log/Handler/Syslog.hs src/System/Log/Handler/Syslog.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28646/src/System/Log/Handler/Growl.hs src/System/Log/Handler/Growl.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28646/src/System/Log/Logger.hs src/System/Log/Logger.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 Creating dist/doc/html/hslogger/ (and its parents) /usr/local/bin/haddock --use-contents=/package/hslogger-1.0.4 --prologue=dist/doc/html/hslogger/haddock-prolog28646.txt --dump-interface=dist/doc/html/hslogger/hslogger.haddock --optghc=-package-name --optghc=hslogger-1.0.4 --source-module=src/%{MODULE/./-}.html --source-entity=src/%{MODULE/./-}.html#%{NAME} --verbosity=1 --html --read-interface=/packages/archive/array/0.3.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/array-0.3.0.0/array.haddock --read-interface=/packages/archive/base/4.2.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/base-4.2.0.0/base.haddock --read-interface=/packages/archive/bytestring/0.9.1.6/doc/html,/usr/local/tmp/archive/install/share/doc/bytestring-0.9.1.6/html/bytestring.haddock --read-interface=/packages/archive/containers/0.3.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/containers-0.3.0.0/containers.haddock --read-interface=/packages/archive/directory/1.0.1.0/doc/html,/usr/local/share/doc/ghc/html/libraries/directory-1.0.1.0/directory.haddock --read-interface=/packages/archive/filepath/1.1.0.3/doc/html,/usr/local/share/doc/ghc/html/libraries/filepath-1.1.0.3/filepath.haddock --read-interface=/packages/archive/ghc-prim/0.2.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/ghc-prim.haddock --read-interface=/packages/archive/integer-gmp/0.2.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/integer-gmp-0.2.0.0/integer-gmp.haddock --read-interface=/packages/archive/mtl/1.1.0.2/doc/html,/usr/local/tmp/archive/install/share/doc/mtl-1.1.0.2/html/mtl.haddock --read-interface=/packages/archive/network/2.2.1.7/doc/html,/usr/local/tmp/archive/install/share/doc/network-2.2.1.7/html/network.haddock --read-interface=/packages/archive/old-locale/1.0.0.2/doc/html,/usr/local/share/doc/ghc/html/libraries/old-locale-1.0.0.2/old-locale.haddock --read-interface=/packages/archive/old-time/1.0.0.3/doc/html,/usr/local/share/doc/ghc/html/libraries/old-time-1.0.0.3/old-time.haddock --read-interface=/packages/archive/parsec/3.1.0/doc/html,/usr/local/tmp/archive/install/share/doc/parsec-3.1.0/html/parsec.haddock --read-interface=/packages/archive/process/1.0.1.2/doc/html,/usr/local/share/doc/ghc/html/libraries/process-1.0.1.2/process.haddock --read-interface=/packages/archive/syb/0.1.0.3/doc/html,/usr/local/tmp/archive/install/share/doc/syb-0.1.0.3/html/syb.haddock --read-interface=/packages/archive/unix/2.4.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/unix-2.4.0.0/unix.haddock --odir=dist/doc/html/hslogger/ --title=hslogger-1.0.4: Versatile logging framework --optghc=-hide-all-packages --optghc=-fbuilding-cabal-package --optghc=-i --optghc=-idist/build --optghc=-isrc --optghc=-idist/build/autogen --optghc=-Idist/build/autogen --optghc=-Idist/build --optghc=-optP-include --optghc=-optPdist/build/autogen/cabal_macros.h --optghc=-odir --optghc=dist/build --optghc=-hidir --optghc=dist/build --optghc=-stubdir --optghc=dist/build --optghc=-package-id --optghc=base-4.2.0.0-c9182baf5cf44f2e72b2298fa160086c --optghc=-package-id --optghc=containers-0.3.0.0-409fe3b8f0dda25b98e03716d26be411 --optghc=-package-id --optghc=directory-1.0.1.0-769c7c4cb13708701fa26cbaa9b7780c --optghc=-package-id --optghc=mtl-1.1.0.2-23ca4de7c573fd4df309067199a40634 --optghc=-package-id --optghc=network-2.2.1.7-e388b0c3a1fbcfbb9d3baf52a1febdd8 --optghc=-package-id --optghc=process-1.0.1.2-8b5308cb23fbdc3c2df27e298550937f --optghc=-package-id --optghc=unix-2.4.0.0-7d42d72856fae71324453279e546294e --optghc=-O --optghc=-O2 --optghc=-XCPP --optghc=-XExistentialQuantification -B/usr/local/lib/ghc-6.12.1 dist/build/tmp28646/src/System/Log.hs dist/build/tmp28646/src/System/Log/Handler.hs dist/build/tmp28646/src/System/Log/Handler/Simple.hs dist/build/tmp28646/src/System/Log/Handler/Syslog.hs dist/build/tmp28646/src/System/Log/Handler/Growl.hs dist/build/tmp28646/src/System/Log/Logger.hs src/System/Log/Logger.hs:333:20: Couldn't match expected type `Maybe Logger' against inferred type `IO Logger' In a stmt of a 'do' expression: result <- Map.lookup lname newlt In the expression: do { let newlt = createLoggers (componentsOfName lname) lt; result <- Map.lookup lname newlt; return (newlt, result) } In a case alternative: Nothing -> do { let newlt = ...; result <- Map.lookup lname newlt; return (newlt, result) } src/System/Log/Logger.hs:349:16: Couldn't match expected type `Maybe a' against inferred type `Either a1 b' In the pattern: Left (_ :: String) In a case alternative: Left (_ :: String) -> findmodellogger lt xs In the expression: case Map.lookup x lt of { Left (_ :: String) -> findmodellogger lt xs Right logger -> logger {handlers = []} } *** Trying again with preferred-versions *** setup configure setup/setup configure --ghc --user --prefix=/usr/local/tmp/archive/install --haddock-option=--use-contents=/package/hslogger-1.0.4 --constraint=base<4 --constraint=parsec<3 --constraint=QuickCheck<2 --constraint=cabal-install<0.8 --verbose Configuring hslogger-1.0.4... Flags chosen: small_base=True Warning: No 'build-type' specified. If you do not need a custom Setup.hs or ./configure script then use 'build-type: Simple'. Dependency base ==3.*: using base-3.0.3.2 Dependency containers -any: using containers-0.3.0.0 Dependency directory -any: using directory-1.0.1.0 Dependency mtl -any: using mtl-1.1.0.2 Dependency network -any: using network-2.2.1.7 Dependency process -any: using process-1.0.1.2 Dependency unix -any: using unix-2.4.0.0 Warning: This package indirectly depends on multiple versions of the same package. This is highly likely to cause a compile failure. package base-3.0.3.2 requires syb-0.1.0.2 package parsec-3.1.0 requires syb-0.1.0.3 Using Cabal-1.8.0.2 compiled by ghc-6.12 Using compiler: ghc-6.12.1 Using install prefix: /usr/local/tmp/archive/install Binaries installed in: /usr/local/tmp/archive/install/bin Libraries installed in: /usr/local/tmp/archive/install/lib/hslogger-1.0.4/ghc-6.12.1 Private binaries installed in: /usr/local/tmp/archive/install/libexec Data files installed in: /usr/local/tmp/archive/install/share/hslogger-1.0.4 Documentation installed in: /usr/local/tmp/archive/install/share/doc/hslogger-1.0.4 Using alex version 2.3.1 found on system at: /usr/bin/alex Using ar found on system at: /usr/bin/ar Using c2hs version 0.16.0 found on system at: /usr/local/bin/c2hs Using cpphs version 1.11 found on system at: /usr/local/bin/cpphs Using ffihugs found on system at: /usr/local/bin/ffihugs Using gcc version 4.4.3 found on system at: /usr/bin/gcc Using ghc version 6.12.1 found on system at: /usr/local/bin/ghc Using ghc-pkg version 6.12.1 found on system at: /usr/local/bin/ghc-pkg Using greencard found on system at: /usr/local/tmp/archive/install/bin/greencard Using haddock version 2.7.2 found on system at: /usr/local/bin/haddock Using happy version 1.17 found on system at: /usr/local/bin/happy No hmake found Using hsc2hs version 0.67 found on system at: /usr/local/bin/hsc2hs Using hscolour version 1.16 found on system at: /usr/local/bin/HsColour Using hugs found on system at: /usr/local/bin/hugs No jhc found Using ld found on system at: /usr/bin/ld No lhc found No lhc-pkg found No nhc98 found Using pkg-config version 0.22 found on system at: /usr/bin/pkg-config Using ranlib found on system at: /usr/bin/ranlib Using strip found on system at: /usr/bin/strip Using tar found on system at: /bin/tar *** setup haddock setup/setup haddock --verbose --html-location=/packages/archive/$pkg/$version/doc/html --hyperlink-source Running Haddock for hslogger-1.0.4... /usr/local/bin/haddock --use-contents=/package/hslogger-1.0.4 --ghc-version Creating dist/build (and its parents) Creating dist/build/autogen (and its parents) Preprocessing library hslogger-1.0.4... Preprocessing executables for hslogger-1.0.4... Running hscolour for hslogger-1.0.4... Creating dist/doc/html/hslogger (and its parents) Creating dist/doc/html/hslogger/src (and its parents) /usr/local/bin/HsColour -print-css -odist/doc/html/hslogger/src/hscolour.css /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log.html src/System/Log.hs /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log-Handler.html src/System/Log/Handler.hs /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log-Handler-Simple.html src/System/Log/Handler/Simple.hs /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log-Handler-Syslog.html src/System/Log/Handler/Syslog.hs /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log-Handler-Growl.html src/System/Log/Handler/Growl.hs /usr/local/bin/HsColour -css -anchor -odist/doc/html/hslogger/src/System-Log-Logger.html src/System/Log/Logger.hs Warning: The documentation for the following packages are not installed. No links will be generated to these packages: base-3.0.3.2, ffi-1.0, rts-1.0 /usr/local/bin/ghc --print-libdir /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28740/src/System/Log.hs src/System/Log.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28740/src/System/Log/Handler.hs src/System/Log/Handler.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28740/src/System/Log/Handler/Simple.hs src/System/Log/Handler/Simple.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28740/src/System/Log/Handler/Syslog.hs src/System/Log/Handler/Syslog.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28740/src/System/Log/Handler/Growl.hs src/System/Log/Handler/Growl.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 /usr/local/bin/ghc -E -cpp -x hs -optP-include -optPdist/build/autogen/cabal_macros.h -o dist/build/tmp28740/src/System/Log/Logger.hs src/System/Log/Logger.hs -Dlinux_BUILD_OS -Dlinux_HOST_OS -Di386_BUILD_ARCH -Di386_HOST_ARCH -D__GLASGOW_HASKELL__=612 Creating dist/doc/html/hslogger/ (and its parents) /usr/local/bin/haddock --use-contents=/package/hslogger-1.0.4 --prologue=dist/doc/html/hslogger/haddock-prolog28740.txt --dump-interface=dist/doc/html/hslogger/hslogger.haddock --optghc=-package-name --optghc=hslogger-1.0.4 --source-module=src/%{MODULE/./-}.html --source-entity=src/%{MODULE/./-}.html#%{NAME} --verbosity=1 --html --read-interface=/packages/archive/array/0.3.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/array-0.3.0.0/array.haddock --read-interface=/packages/archive/base/4.2.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/base-4.2.0.0/base.haddock --read-interface=/packages/archive/bytestring/0.9.1.6/doc/html,/usr/local/tmp/archive/install/share/doc/bytestring-0.9.1.6/html/bytestring.haddock --read-interface=/packages/archive/containers/0.3.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/containers-0.3.0.0/containers.haddock --read-interface=/packages/archive/directory/1.0.1.0/doc/html,/usr/local/share/doc/ghc/html/libraries/directory-1.0.1.0/directory.haddock --read-interface=/packages/archive/filepath/1.1.0.3/doc/html,/usr/local/share/doc/ghc/html/libraries/filepath-1.1.0.3/filepath.haddock --read-interface=/packages/archive/ghc-prim/0.2.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/ghc-prim.haddock --read-interface=/packages/archive/integer-gmp/0.2.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/integer-gmp-0.2.0.0/integer-gmp.haddock --read-interface=/packages/archive/mtl/1.1.0.2/doc/html,/usr/local/tmp/archive/install/share/doc/mtl-1.1.0.2/html/mtl.haddock --read-interface=/packages/archive/network/2.2.1.7/doc/html,/usr/local/tmp/archive/install/share/doc/network-2.2.1.7/html/network.haddock --read-interface=/packages/archive/old-locale/1.0.0.2/doc/html,/usr/local/share/doc/ghc/html/libraries/old-locale-1.0.0.2/old-locale.haddock --read-interface=/packages/archive/old-time/1.0.0.3/doc/html,/usr/local/share/doc/ghc/html/libraries/old-time-1.0.0.3/old-time.haddock --read-interface=/packages/archive/parsec/3.1.0/doc/html,/usr/local/tmp/archive/install/share/doc/parsec-3.1.0/html/parsec.haddock --read-interface=/packages/archive/process/1.0.1.2/doc/html,/usr/local/share/doc/ghc/html/libraries/process-1.0.1.2/process.haddock --read-interface=/packages/archive/syb/0.1.0.2/doc/html,/usr/local/share/doc/ghc/html/libraries/syb-0.1.0.2/syb.haddock --read-interface=/packages/archive/syb/0.1.0.3/doc/html,/usr/local/tmp/archive/install/share/doc/syb-0.1.0.3/html/syb.haddock --read-interface=/packages/archive/unix/2.4.0.0/doc/html,/usr/local/share/doc/ghc/html/libraries/unix-2.4.0.0/unix.haddock --odir=dist/doc/html/hslogger/ --title=hslogger-1.0.4: Versatile logging framework --optghc=-hide-all-packages --optghc=-fbuilding-cabal-package --optghc=-i --optghc=-idist/build --optghc=-isrc --optghc=-idist/build/autogen --optghc=-Idist/build/autogen --optghc=-Idist/build --optghc=-optP-include --optghc=-optPdist/build/autogen/cabal_macros.h --optghc=-odir --optghc=dist/build --optghc=-hidir --optghc=dist/build --optghc=-stubdir --optghc=dist/build --optghc=-package-id --optghc=base-3.0.3.2-52acef427378232ec569bca0486ee48f --optghc=-package-id --optghc=containers-0.3.0.0-409fe3b8f0dda25b98e03716d26be411 --optghc=-package-id --optghc=directory-1.0.1.0-769c7c4cb13708701fa26cbaa9b7780c --optghc=-package-id --optghc=mtl-1.1.0.2-23ca4de7c573fd4df309067199a40634 --optghc=-package-id --optghc=network-2.2.1.7-e388b0c3a1fbcfbb9d3baf52a1febdd8 --optghc=-package-id --optghc=process-1.0.1.2-8b5308cb23fbdc3c2df27e298550937f --optghc=-package-id --optghc=unix-2.4.0.0-7d42d72856fae71324453279e546294e --optghc=-O --optghc=-O2 --optghc=-XCPP --optghc=-XExistentialQuantification -B/usr/local/lib/ghc-6.12.1 dist/build/tmp28740/src/System/Log.hs dist/build/tmp28740/src/System/Log/Handler.hs dist/build/tmp28740/src/System/Log/Handler/Simple.hs dist/build/tmp28740/src/System/Log/Handler/Syslog.hs dist/build/tmp28740/src/System/Log/Handler/Growl.hs dist/build/tmp28740/src/System/Log/Logger.hs src/System/Log/Logger.hs:333:20: Couldn't match expected type `Maybe Logger' against inferred type `IO Logger' In a stmt of a 'do' expression: result <- Map.lookup lname newlt In the expression: do { let newlt = createLoggers (componentsOfName lname) lt; result <- Map.lookup lname newlt; return (newlt, result) } In a case alternative: Nothing -> do { let newlt = ...; result <- Map.lookup lname newlt; return (newlt, result) } src/System/Log/Logger.hs:349:16: Couldn't match expected type `Maybe a' against inferred type `Either a1 b' In the pattern: Left (_ :: String) In a case alternative: Left (_ :: String) -> findmodellogger lt xs In the expression: case Map.lookup x lt of { Left (_ :: String) -> findmodellogger lt xs Right logger -> logger {handlers = []} }