Proposal: Add a strictly accumulating scanl' to Data.List
Joachim Breitner wrote, in https://ghc.haskell.org/trac/ghc/ticket/9345#comment:6, a strictly accumulating version of scanl, to be named scanl'. I was initially concerned about its safety for fusion, but am now convinced of its correctness and believe it should be added to Data.List. scanl' :: (b -> a -> b) -> b -> [a] -> [b] scanl' f a bs = build $ \c n -> a `seq` a `c` foldr (\b g x -> (let b' = f x b in b' `seq` (b' `c` g b'))) (\b -> b `seq` n) bs a
There's been no response to this so far, and I'd like to get it for 7.10.1. Any opinions? Joachim Breitner wrote, in https://ghc.haskell.org/trac/ghc/ticket/9345#comment:6, a strictly accumulating version of scanl, to be named scanl'. I was initially concerned about its safety for fusion, but am now convinced of its correctness and believe it should be added to Data.List. scanl' :: (b -> a -> b) -> b -> [a] -> [b] scanl' f a bs = build $ \c n -> a `seq` a `c` foldr (\b g x -> (let b' = f x b in b' `seq` (b' `c` g b'))) (\b -> b `seq` n) bs a
Hi, Am Montag, den 27.10.2014, 19:04 -0400 schrieb David Feuer:
There's been no response to this so far, and I'd like to get it for 7.10.1. Any opinions?
I’m fine with the addition. (Generally, complete silence can be taken as mild agreement from everyone :-)) Greetings, Joachim -- Joachim “nomeata” Breitner mail@joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nomeata@joachim-breitner.de • GPG-Key: 0xF0FBF51F Debian Developer: nomeata@debian.org
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Me too. It just bothers me a bit that the 4th line's call to seq uses parenthesis while the 3rd's doesn't :).
Em 28 de outubro de 2014 07:33:43 BRST, Joachim Breitner
Hi,
Am Montag, den 27.10.2014, 19:04 -0400 schrieb David Feuer:
There's been no response to this so far, and I'd like to get it for 7.10.1. Any opinions?
I’m fine with the addition.
(Generally, complete silence can be taken as mild agreement from everyone :-))
Greetings, Joachim -- Joachim “nomeata” Breitner mail@joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nomeata@joachim-breitner.de • GPG-Key: 0xF0FBF51F Debian Developer: nomeata@debian.org
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participants (3)
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David Feuer -
Felipe Lessa -
Joachim Breitner