#7021: Tuple (and other exotic predicates) not yet handled in Template Haskell -------------------------+------------------------------------------------- Reporter: | Owner: goldfire | Status: new Type: | Milestone: 7.8.1 feature request | Version: 7.5 Priority: | Keywords: ConstraintKinds normal | TemplateHaskell Component: | Architecture: Unknown/Multiple Template Haskell | Difficulty: Unknown Resolution: | Blocked By: Operating System: | Related Tickets: Unknown/Multiple | Type of failure: | None/Unknown | Test Case: | Blocking: | -------------------------+------------------------------------------------- Comment (by goldfire): Thanks for sharing your patch. Here are some further comments: * The `EqualityT` constructor has type `Type -> Type -> Type`. Yet, this would prevent encoding constructs like `[t| ((~) Int) |]`, which should be valid. I recommend putting `EqualityT` in like `ArrowT` is now, as a nullary (0-argument) constructor. * The `foldM` and `go` algorithm (lines 65-67) you use seems like `repTapps`. Or, am I missing something? * In reifying an `IrredPred`, you use `splitAppTy`... but we're not sure there that the type is an application. For example, it could be a nullary type family, like this: {{{ type family ALittleSilly :: Constraint }}} I believe this would be an `IrredPred`, if there are no instances for the type family. (I haven't tested it.) I will say that I appreciate your attention to detail to GHC's coding style. I hope all these comments don't put you off -- we do really appreciate your contribution! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/7021#comment:13 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler