#13887: Template Haskell pretty-printer doesn't parenthesize infix datatype names in data declarations -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Template Haskell | Version: 8.0.1 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by ak3n): I am not sure, but I think that it's enough to change `pprName' Alone` to `pprName' Applied` [https://git.haskell.org/ghc.git/blob/HEAD:/libraries /template-haskell/Language/Haskell/TH/PprLib.hs#l123 here]. There are 8 failed tests in `testsuite/tests/th` because of this change: - `GHC.Types.:` becomes `(GHC.Types.:)` - `Data.Type.Equality.~` becomes `(Data.Type.Equality.~)` - and something else There is another way to fix it. Change `ppr t` to `pprName' Applied t` [https://git.haskell.org/ghc.git/blob/HEAD:/libraries/template- haskell/Language/Haskell/TH/Ppr.hs#l401 here], which outputs: {{{ data (:~:_0) a_1 b_2 where Refl1_3 :: :~:_0 a_4 a_4 data (:~~:_0) a_1 b_2 = a_1 ~ b_2 => Refl2_3 }}} This [https://git.haskell.org/ghc.git/blob/HEAD:/libraries/template- haskell/Language/Haskell/TH/Ppr.hs#l402 line] is responsible for the kind of `Refl1_3`, but I haven't figured out how to fix it yet. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13887#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler