#5683: bug in signum function -------------------------------------+------------------------------------- Reporter: tristes_tigres | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.6.1 Component: Prelude | Version: 7.0.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by johnw42): Aside from preserving NaN, there's also a question of whether -0.0 should be mapped to 0.0 or left alone. IMHO it should be left unchanged because it permits a nice symmetric implementation: {{{#!hs signum x | x > 0 = 1 | x < 0 = -1 | otherwise = x }}} Aside: there's some good discussion [http://stackoverflow.com/questions/1986152/why-doesnt-python-have-a-sign- function here] of why Python has no signum function. I guess that ship has sailed for Haskell, but it makes me inclined to think there's no universally correct definition, which is why I think having a pretty implementation is as good a reason as any to settle on a definition for the edge cases. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/5683#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler