Resolving dependencies...
Downloading sessions-2007.6.17...
[1 of 1] Compiling Main             ( /tmp/sessions-2007.6.17-13461/sessions-2007.6.17/Setup.hs, /tmp/sessions-2007.6.17-13461/sessions-2007.6.17/dist/setup/Main.o )
Linking /tmp/sessions-2007.6.17-13461/sessions-2007.6.17/dist/setup/setup ...
Configuring sessions-2007.6.17...
Warning: No 'build-type' specified. If you do not need a custom Setup.hs or
./configure script then use 'build-type: Simple'.
Building sessions-2007.6.17...
Preprocessing library sessions-2007.6.17...

Control/Concurrent/Session/BaseClasses.hs:20:16: Warning:
    -fglasgow-exts is deprecated: Use individual extensions instead

Control/Concurrent/Session/BaseClasses.hs:20:16: Warning:
    -fallow-undecidable-instances is deprecated: use -XUndecidableInstances or pragma {-# LANGUAGE UndecidableInstances #-} instead

Control/Concurrent/Session/BaseClasses.hs:20:16: Warning:
    -fallow-overlapping-instances is deprecated: use -XOverlappingInstances or pragma {-# LANGUAGE OverlappingInstances #-} instead

Control/Concurrent/Session/BaseTypes.hs:20:16: Warning:
    -fglasgow-exts is deprecated: Use individual extensions instead

Control/Concurrent/Session/Choice.hs:20:16: Warning:
    -fglasgow-exts is deprecated: Use individual extensions instead

Control/Concurrent/Session/Choice.hs:20:16: Warning:
    -fallow-undecidable-instances is deprecated: use -XUndecidableInstances or pragma {-# LANGUAGE UndecidableInstances #-} instead

Control/Concurrent/Session/ExtraClasses.hs:20:16: Warning:
    -fglasgow-exts is deprecated: Use individual extensions instead

Control/Concurrent/Session/List.hs:20:16: Warning:
    -fglasgow-exts is deprecated: Use individual extensions instead

Control/Concurrent/Session/List.hs:20:16: Warning:
    -fallow-undecidable-instances is deprecated: use -XUndecidableInstances or pragma {-# LANGUAGE UndecidableInstances #-} instead

Control/Concurrent/Session/Loop.hs:20:16: Warning:
    -fglasgow-exts is deprecated: Use individual extensions instead

Control/Concurrent/Session/Loop.hs:20:16: Warning:
    -fallow-undecidable-instances is deprecated: use -XUndecidableInstances or pragma {-# LANGUAGE UndecidableInstances #-} instead

Control/Concurrent/Session/Loop.hs:20:16: Warning:
    -fallow-overlapping-instances is deprecated: use -XOverlappingInstances or pragma {-# LANGUAGE OverlappingInstances #-} instead

Control/Concurrent/Session/Runtime.hs:20:16: Warning:
    -fglasgow-exts is deprecated: Use individual extensions instead

Control/Concurrent/Session/Runtime.hs:20:16: Warning:
    -fallow-undecidable-instances is deprecated: use -XUndecidableInstances or pragma {-# LANGUAGE UndecidableInstances #-} instead

Control/Concurrent/Session/Runtime.hs:20:16: Warning:
    -fallow-overlapping-instances is deprecated: use -XOverlappingInstances or pragma {-# LANGUAGE OverlappingInstances #-} instead

Control/Concurrent/Session/State.hs:20:16: Warning:
    -fglasgow-exts is deprecated: Use individual extensions instead
[1 of 9] Compiling Control.Concurrent.Session.List ( Control/Concurrent/Session/List.hs, dist/build/Control/Concurrent/Session/List.o )

Control/Concurrent/Session/List.hs:25:1:
    Illegal generalised algebraic data declaration for `List'
      (Use -XGADTs to allow GADTs)
    In the data declaration for `List'
Failed to install sessions-2007.6.17
cabal: Error: some packages failed to install:
sessions-2007.6.17 failed during the building phase. The exception was:
ExitFailure 1