#15646: ghci takes super long time to find the type of large fractional number -------------------------------------+------------------------------------- Reporter: Johannkokos | Owner: | JulianLeviston Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: GHCi | Version: 8.4.3 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by osa1): Right, so there's a brief discussion about this in comment:29, however we can't convert a `Rational` to the new `FractionalLit` type so the idea doesn't quite work. Changing TH syntax is not easy becuase it's a user-facing type (would need a proposal). One idea comes to mind is to make `FractionalLit` a sum type, with an alternative for the old `FractionalLit` values: {{{ data FractonalLit = FL { ... } -- | TemplateHaskell fractional lit: we lose information during conversion -- from Haskell syntax to TH syntax (happens when desugaring quasiquotes, in -- DsMeta) where we convert a `FL` to a `Rational` because that's what TH -- syntax wants. | THFL { fl_text :: SourceText , fl_next :: Bool , fl_value :: Rational } }}} Then we can propose a change to the TH syntax, depending on the result we can remove the `THFL` constructor. Alternatively, Simon suggests finding an approximate conversion of a `Rational` to the new `FractionalLit` in comment:30. That'd fine to get the code to compile but it won't be mergeable until the conversion is fixed. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15646#comment:37 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler