#10858: Smaller generated Ord instances -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 Resolution: | Keywords: deriving-perf Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #9557 | Differential Rev(s): D2502 Wiki Page: | -------------------------------------+------------------------------------- Changes (by prokhorenkov): * differential: => D2502 Comment: May I interest you all with a really ''newcomer-grade'' change? We can just generate "compare" and "<" as usual and express other relations through "<". Like {{{ a > b = b < a a <= b = not $ b < a a >= b = not $ a < b }}} This saves us code for 3 methods out of 5 for a small added cost of extra negation. When the code for "<" is short enough the inliner would make the code as good as can be. Otherwise added negation would be insignificant. Adding new differential rev with the proposed changes. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10858#comment:17 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler