Hi all, I'm writing a small module that exposes a template haskell splice that takes a (very simplified) C struct definition and builds: - A data type definition, - an instance for Data.Binary.Binary, - and optionally a pretty print function for it However, it seems to do this I have to write a bunch of really ugly code that builds up the TH data structures "by hand" because quoting only works with splices for expressions, or so it seems. For example, to generate the binary instance I have this code: import qualified Language.Haskell.TH as TH -- tyname is the name of the data type I've already created, as a TH.Name -- tempnames is a list of temporary variable names that are used in lambda patterns -- fields is a list of tuples describing each field -- makeGetExp recursively builds a monadic computation consisting mostly of Binary.getWord32be >>= \ tempvar -> ... binaryInstDec <- liftM (TH.InstanceD [] (TH.AppT (TH.ConT $ TH.mkName "Data.Binary.Binary") (TH.ConT tyname))) [d| get = $(makeGetExp (reverse $ zip fields tempnames) returnExp) put = undefined |] I'd really rather write: binaryInstDec <- [d| instance Binary.Binary $(tyname) where get = $(makeGetExp (reverse $ zip fields tempnames) returnExp) put = undefined |] But GHC gives me a syntax error on the tyname splice. The docs seem to indicate this is the way it is -- that splices in type locations is plain not implemented. My question is whether or not this is just the way it is, and people writing TH declaration splices tend to have to start manually assembling a bunch of it, or is there some trick I've missed? Perhaps even better are there some tricks that people tend to use to make this less painful? I did try using some of the lowercased monadic constructors in Language.Haskell.TH.Lib but I didn't seem to get anything more succint out of it. -Ross P.S. This is for a one-off weekend project, and the code is fugly, so I'm not posting it in its entirety here. If you want the whole module and are willing not to laugh, I'd be glad to send it along ;-) Background: I'm doing this because I'm writing a tool to snoop around the filesystem structures of HFS+ to try and help a friend recover some data off a sufficiently dead drive that fsck doesn't want to touch it, and I don't want to pay money just to find out the drive is too toasty to pull out the data. In any case, the HFS+ docs have a bunch of C struct definitions that comprise the structures, and I got tired of hand-writing data definitions and binary instances, so I figured I'd make TH do it for me.