[Template-haskell] Stuck... is it even possible?

[Tim Newsham]

I'm having problems with my template generator.  I have everything
working except for the "flen" function which I'm faking for now:

    http://lava.net/~newsham/x/jethr0/

The directory has 4 source files (with or without .txt extensions for
your browsing enjoyment):

   ByteContainer.lhs   - defining my classes
   IP.lhs              - defining my test data type
   Gen.lhs             - defining my TH generator
   tst.lhs             - my test case.

You can see it go by running "ghc -c -fth -ddump-splices tst.lhs".

The problem:  flen should compute and return the size of each field.
Concretely:

     flen ("Word8",_,_)    should compute "containerLength newWord8"
     flen ("Word16",_,_)   should compute "containerLength newWord16"
     flen ("IP",_,_)       should compute "containerLength newIP"
     flen (n,_,_)          should compute "containerLength" of ("new"++n)

The flen function is used during template generation, and needs to
know the integer length while expanding the template (ie. flen doesnt
generate anything).

Is this possible?

Tim Newsham
http://www.lava.net/~newsham/