Fix #14: efficient tail instance for difference list #15
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PR #5 offered a workaround for the regression in `dlist-1.0` which changed the type of the `tail` function for difference lists (so it does not have the type `DList a -> DList a` of a tail function anymore). The problem with #5 is that it collapses the difference list to compute its tail. Here, we offer a solution that does not collapse the difference list, by precomposing the `Data.List.tail` with the underlying function `[a] -> [a]` of a difference list. Data.List.Unsafe gives us access to this function. This problem would better be fixed upstream, see spl/dlist#98
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This looks trustworthy to me. |
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Am I still the maintainer of listlike? Maybe I should step down. I'm just merging pull requests reflexively. |
You already made me co-maintainer, giving me all the powers needed (write access and release permissions). If you want, I can also take over officially as "main-maintainer". In general, I think it is good to have several maintainers, as sometimes one becomes unresponsive, and then there are others to step up... |
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Fix #14: efficient tail instance for difference list.
PR #5 offered a workaround for the regression in
dlist-1.0which changed the type of thetailfunction for difference lists (so it does not have the typeDList a -> DList aof a tail function anymore).The problem with #5 is that it collapses the difference list to compute its tail.
Here, we offer a solution that does not collapse the difference list, by precomposing the
Data.List.tailwith the underlying function[a] -> [a]of a difference list.Data.List.Unsafegives us access to this function.This problem would better be fixed upstream, see spl/dlist#98.