#12249: Template Haskell top level scoping error -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Template Haskell | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): Hm. I suppose I've run into the same issue when writing `singletons`. But isn't this what `newName` is for? Currently, `newName` doesn't always do a good enough job at creating a top-level name that's fresh even between splices, but I'm sure we could fix it. In effect, you're trying to turn TH into a module/namespace system, where some apparently-top-level declarations actually have a limited scope. Whether or not a definition is local or global depends on the entire file, instead of being listed in one spot. While what you propose may be readily implementable, I would say that it may be time better spent designing a proper module/namespace system that TH could use. As you've designed this feature, I could see people (perhaps even including myself) using TH only for your new module-like capabilities. For example, when writing papers, I often use the same variable names in different examples. When I extract my code and compile the papers, these overlapping variable names cause annoyance. If you implement your feature, then I would put some TH dingbats in my extraction engine to avoid the ambiguous variable uses/redefinitions... but this is abusive of TH. Clearly, compiling academic papers is not the primary use-case for Haskell (or is it? I suppose it once was!) but I'm sure I'm not the only one who would do such shenanigans. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12249#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler