Re: [GHC] #14343: bad pretty-printing of types with promoted data types

#14343: bad pretty-printing of types with promoted data types -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: andreash Type: bug | Status: closed Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.2.1 Resolution: fixed | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4746 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones ): In [changeset:"ae2c9b40f5b6bf272251d1f4107c60003f541b62/ghc" ae2c9b40/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="ae2c9b40f5b6bf272251d1f4107c60003f541b62" Smarter HsType pretty-print for promoted datacons Fix Trac #15898, by being smarter about when to print a space before a promoted data constructor, in a HsType. I had to implement a mildly tiresome function HsType.lhsTypeHasLeadingPromotionQuote It has multiple cases, of course, but it's very simple. The patch improves the error-message output in a bunch of cases, and (to my surprise) actually fixes a bug in the output of T14343 (Trac #14343), thus - In the expression: _ :: Proxy '('( 'True, 'False), 'False) + In the expression: _ :: Proxy '( '( 'True, 'False), 'False) I discovered that there were two copies of the PromotionFlag type (a boolean, with helpfully named data cons), one in IfaceType and one in HsType. So I combined into one, PromotionFlag, and moved it to BasicTypes. That's why quite a few files are touched, but it's all routine. }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14343#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler