[Haskell-cafe] TH error

Tim Newsham newsham at lava.net
Fri Sep 26 22:33:54 EDT 2008

I'm goofing with TH and I have my program mostly done:


If I have the "$(deriveBinary ''MyData)" line commented out it
prints out what looks to me like correct code.  I can even paste
it into a program and it compiles.  However, when the line isn't
commented out I get an error I don't understand:

         Illegal data constructor name: `x'
         When splicing generated code into the program

There are two places in my code I use "x" in splices that could
be causing the problem:

     g <- [| getWord8 >>= \x -> $(caseE [| x |] gcases') |]
               put x = $(caseE [| x |] (map return ps)) |]

but I don't understand why these might be causing errors (if they
are indeed the cause).  Using -ddump-splices doesn't help since
it seems to hit the error before dumping splices.

What's going on here?

Tim Newsham

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