[Haskell-cafe] deepseq-1.2.0.1 missing Data.Map instance

Henry Laxen nadine.and.henry at pobox.com
Tue Nov 15 23:26:04 CET 2011


Dear Group,

Today I tried to compile snap 0.6 with ghc 7.2, (using virthualenv,
which is GREAT by the way) and got the following
error somewhere along the way got a message about aeson-native
requires deepseq-1.1.0.2 but I had deepseq-1.2.0.1 installed.  So I
unpacked aeson-native-0.3.3.1 in my virthualenv and changed the
build-depends to just deepseq which caused:

Configuring aeson-native-0.3.3.1...
Preprocessing library aeson-native-0.3.3.1...
Building aeson-native-0.3.3.1...
[2 of 6] Compiling Data.Aeson.Types ( Data/Aeson/Types.hs, 
dist/build/Data/Aeson/Types.o )

Data/Aeson/Types.hs:196:22:
    No instance for (NFData Object)
      arising from a use of `rnf'
    Possible fix: add an instance declaration for (NFData Object)
    In the expression: rnf o
    In an equation for `rnf': rnf (Object o) = rnf o
    In the instance declaration for `NFData Value'
cabal: Error: some packages failed to install:
aeson-native-0.3.3.1 failed during the building phase. The exception was:
ExitFailure 1


A little investigating and I discovered that

instance (NFData k, NFData a) => NFData (Data.Map.Map k a) where
    rnf = rnf . Data.Map.toList


is in deepseq-1.1.0.2 but not in deepseq-1.2.0.1.  Adding it back got
aeson-native-0.3.3.1 and later snap-0.6 to compile just fine.  So I
guess my question is:  Is there a reason that the map instance was
removed from deepseq-1.2.0.1, and can we please put it back in?
Thanks.

Best wishes,
Henry Laxen





More information about the Haskell-Cafe mailing list