#14265: kinded holes -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.2.1 checker) | Keywords: Resolution: | PartialTypeSignatures 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 lspitzner): That is exactly what I meant. Polykinded was not even in my mind; it would not hurt to have the same in simpler (non-polykind) cases too, like {{{#!hs foo :: StateT _ _ (); foo = undefined }}} could produce {{{ <interactive>:7:15: error: • Found type wildcard ‘_’ standing for ‘w’ (of kind ‘*’) Where: ‘w’ is a rigid type variable bound by the inferred type of foo :: StateT w w1 () at <interactive>:7:23-37 To use the inferred type, enable PartialTypeSignatures • In the type signature: foo :: StateT _ _ () <interactive>:7:17: error: • Found type wildcard ‘_’ standing for ‘w1’ (of kind ‘* -> *’) … }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14265#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler