#4385: Type-level natural numbers ----------------------------------------+----------------------------------- Reporter: diatchki | Owner: diatchki Type: feature request | Status: new Priority: normal | Milestone: 7.6.2 Component: Compiler (Type checker) | Version: Keywords: | Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: | Testcase: Blockedby: | Blocking: Related: | ----------------------------------------+----------------------------------- Comment(by darchon): I get a similar error implementing concat for vectors: {{{ data Vec :: Nat -> * -> * where Nil :: Vec 0 a (:>) :: a -> Vec n a -> Vec (n + 1) a vappend :: Vec n a -> Vec m a -> Vec (n + m) a vappend Nil ys = ys vappend (x :> xs) ys = x :> (vappend xs ys) vconcat :: Vec n (Vec m a) -> Vec (n * m) a vconcat Nil = Nil vconcat (x :> xs) = vappend x (vconcat xs) }}} -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/4385#comment:60 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler