Hi, Am Donnerstag, den 13.11.2014, 05:22 -0500 schrieb David Feuer:
Currently, GHC.Arr.listArray is pretty lazy:
listArray (1,3) $ [1,2,3] ++ undefined
will work perfectly fine.
This is actually lazier than the current array:
array (1,3) $ [(1,1), (2,2), (3,3)] ++ undefined = undefined
Unfortunately, I don't think it's possible to make listArray fuse with a list producer while preserving quite that level of laziness. If we're willing to be slightly stricter, however, I think everything works. Specifically, I propose that we allow
listArray (length xs) (xs ++ _|_) = _|_>
given that listArray (1,3) xs = listArray (1,3) (take 3 (xs)) and take can fuse with a good producer (can it?), I would expect that listArray can be made to fuse as good or as bad as take. What precisely is the problem with the more lazy listArray? 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