#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: 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): I am fine with '[' being lexed as it is, so i don't mind a wont-fix for that aspect. But why does the error message for syntactically valid input contain source fragments that are not syntactically valid? Just as a test for how input is transformed (on 8.2.1 as well): {{{ Prelude> _ :: Proxy '[ 'True ] -- 2 spaces in input <interactive>:8:1: error: • Found hole: _ :: Proxy '['True] -- 0 spaces • In the expression: _ :: Proxy '[ 'True] -- 1 spaces In an equation for ‘it’: it = _ :: Proxy '[ 'True] -- 1 spaces • Relevant bindings include it :: Proxy '['True] (bound at <interactive>:8:1) -- 0 spaces }}} The zeros are problematic, and i think the ones only avoid the problem because they don't really re-layout, they just merge whitespace (at least that's what i suspect; haven't looked at the source). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14343#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler