#11387: Typecasting using type application syntax -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: Keywords: | Operating System: Unknown/Multiple TypeApplications | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #11350 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I created #11350 to allow visible (static) type applications in patterns. I had a [https://ghc.haskell.org/trac/ghc/ticket/11350#comment:2 thought] about translating non-parametric type applications in patterns as a runtime type check (`Typeable`) and decided to create a ticket in case it made any sense. Example: {{{#!hs doubleWhenInt :: forall a. Typeable a => a -> a doubleWhenInt x = case eqT @Int @a of Just Refl -> x + x Nothing -> x -- Becomes… doubleWhenInt :: Typeable a => a -> a doubleWhenInt @Int n = n + n doubleWhenInt @_ x = x }}} Thoughts? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11387 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler