GHC 7.4.2 crashes with a panic when using type families and data kinds together

I have no idea how to isolate this bug, since it seems to span multiple modules. If I recompile the entire program (by doing a cabal clean beforehand) the bug disappears. But if I just touch one of the files and try to recompile, it gives me:

compiler output

[3 of 4] Compiling Checker          ( Checker.hs, dist/build/Hammer/Hammer-tmp/Checker.o )
ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.2 for x86_64-unknown-linux):
        tyThingTyCon Data constructor `main:Types.Succ{d r2k}'

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

The code I'm working on is at https://github.com/niuk/Hammer/tree/66c3dda3ec829179b859d37c5bad5b6b2009a9f6.

The crash happens in both Linux and Windows, using packages from Haskell Platform.

Trac metadata

Trac field	Value
Version	7.4.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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