#14343: bad pretty-printing of types with promoted data types -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * keywords: => newcomer Comment: This is just a deficiency of GHC's pretty-printer. It should be relatively straightforward to change it such that GHC inserts a space between `'[` and `'True`. See the [http://git.haskell.org/ghc.git/blob/6a9b9b431dcc94849d14c13639eb2f713e5aa1f4... pprIfaceTyList] function, which is responsible for pretty-printing promoted lists. Note that similar considerations also apply for promoted tuple constructors: {{{ λ> f :: Proxy _ -> Proxy '( 'True, 'True); f x = x <interactive>:5:12: error: • Found type wildcard ‘_’ standing for ‘'('True, 'True) :: (Bool, Bool)’ To use the inferred type, enable PartialTypeSignatures • In the type signature: f :: Proxy _ -> Proxy '( 'True, 'True) }}} So an analogous fix would be needed for the [http://git.haskell.org/ghc.git/blob/6a9b9b431dcc94849d14c13639eb2f713e5aa1f4... pprTuple] function. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14343#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler