Re: More Data.Set and Data.Map operations

I had another idea for an operation that covers most of the likely use-cases for mergeWithKey, but without its danger and with a substantially more informative type signature. The only downside is that it's not even close to Haskell 98. data MergeTactic k x y where Drop :: MergeTactic k x y Preserve :: MergeTactic k x x MapFilter :: (k -> x -> Maybe y) -> MergeTactic k x y generalMerge :: Ord k => (k -> a -> b -> Maybe c) -> MergeTactic k a c -> MergeTactic k b c -> Map k a -> Map k b -> Map k c How do people feel about exporting this for GHC? On Sun, Aug 7, 2016 at 12:32 AM, Oleg Grenrus wrote:

-1 on unionWithMapping/Key. There is already mergeWithKey (and there’s pull request to `these` to use it, I’d just hadn’t time to look it thru properly and apply).

- Oleg Grenrus (co-maintainer of these)

...

On 07 Aug 2016, at 06:15, David Feuer wrote:

Cale Gibbard and Ryan Trinkle are interested in adding some more operations they say will be useful in their work. Note that unionWithMapping is intended to enable an efficient implementation of alignWith in Data.Align in the `these` package.

Set:

filterIncreasing :: Ord a => (a -> Bool) -> Set a -> Set a filterDecreasing :: Ord a => (a -> Bool) -> Set a -> Set a partitionIncreasing :: Ord a => (a -> Bool) -> Set a -> (Set a, Set a)

Map:

filterKeysIncreasing :: Ord k => (k -> Bool) -> Map k a -> Map k a filterKeysDecreasing :: Ord k => (k -> Bool) -> Map k a -> Map k a partitionKeysIncreasing :: Ord k => (k -> Bool) -> Map k a -> (Map k a, Map k a)

traverseMaybe :: Applicative f => (a -> f (Maybe b)) -> Map k a -> f (Map k b)

alterMany :: Ord k => (a -> Maybe b -> Maybe b) -> Map k a -> Map k b -> Map k b

alterManyA :: (Applicative f, Ord k) => (a -> Maybe b -> f (Maybe b)) -> Map k a -> Map k b -> f (Map k b)

unionWithMapping :: Ord k => (a -> c) -> (b -> c) -> (a -> b -> c) -> Map k a -> Map k b -> Map k c

unionWithKeyMapping :: Ord k => (k -> a -> c) -> (k -> b -> c) -> (k -> a -> b -> c) -> Map k a -> Map k b -> Map k c _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries