Sounds somewhat plausible. By all means give it a try. S
-----Original Message----- From: ghc-devs [mailto:ghc-devs-boun...@haskell.org] On Behalf Of Andrew Farmer Sent: 10 August 2016 04:22 To: ghc-devs@haskell.org Subject: enumFromThenTo for Doubles Noticed this today: ghci> let xs = [0.0,0.1 .. 86400.0] in maximum xs 86400.0000005062 enumFromThenTo is implemented by numericEnumFromThenTo: https://github.com/ghc/ghc/blob/a90085bd45239fffd65c01c24752a9bbcef346f1/libraries/base/GHC/Real.hs#L227 Which probably accumulates error in numericEnumFromThen with the (m+m-n): numericEnumFromThen n m = n `seq` m `seq` (n : numericEnumFromThen m (m+m-n)) Why not define numericEnumFromThen as: numericEnumFromThen n m = let d = m - n in d `seq` go d n where go delta x = x `seq` (x : go delta (x + delta)) (or with BangPatterns) numericEnumFromThen n m = go (m - n) n where go !delta !x = x : go delta (x + delta) Seems like we'd save a lot of subtractions by using the worker function. _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fmail.haskell.org%2fcgi-bin%2fmailman%2flistinfo%2fghc-devs&data=02%7c01%7csimonpj%40microsoft.com%7c65f112900fb44b7186a408d3c0cd8631%7c72f988bf86f141af91ab2d7cd011db47%7c1%7c0%7c636063961357184976&sdata=Gz0DQ%2fGEUIyfHtmAjdbxpBt3YEnxbpoKKiygnCb%2fhYo%3d _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
