bokesan / intervalmap Goto Github PK

The interface here is close to the standard Data.Map but it lacks lookupLE (lookup less than or equal) and lookupGE (greater or equal). I am using intervals to cover time periods but there are times that no interval covers, so in that case I need to be able to find the closest match on either side. I realise I could use split for this but for what I want I would need to do something like

IMap.split i >>> IMap.findMax *** IMap.findMin $ imap

but it may be possible to do this more efficiently in the library. If it is not, this issue can be closed.

Any open or half-open interval with the same lower and upper bound should be considered empty (i.e. (x,x], [x,x) and (x,x)). The function IntervalMap.isEmpty agrees with this interpretation, where IntervalMap.isEmpty (IntervalCO 1 1) is True. However, this is not consistent with the results of IntervalMap.intersecting or IntervalMap.overlaps, since an empty interval should never intersect or overlap with any other interval.

Current behavior: IntervalMap.overlaps (IntervalCO 1 1) (InvervalCO 0 2) is True
Expected behavior: IntervalMap.overlaps (IntervalCO 1 1) (InvervalCO 0 2) should be False

Current behavior :IntervalMap.intersecting (fromList [(IntervalCO 0 2, "0_2")]) (IntervalCO 1 1) is [(IntervalCO 0 2, "0_2")]
Expected behavior: IntervalMap.intersecting (fromList [(IntervalCO 0 2, "0_2")]) (IntervalCO 1 1) should be []

I'm sure it's a minor oversight: Is Data.IntervalMap.Strict's lookup function really supposed to take a list of assocs?

import qualified Data.IntervalMap.Strict as IM

fun :: IM.IntervalMap Int String
fun ivmap k v =
  case IM.lookup k ivmap of
    Just _x -> "Good"
    Nothing -> "Bad"

GHC error:

 Couldn't match expected type ‘[(Int, IM.IntervalMap Int String)]'
               with actual type ‘IM.IntervalMap Int String’

Add semigroup instances.
See also: https://ghc.haskell.org/trac/ghc/wiki/Migration/8.4#SemigroupMonoidsuperclasses

Building library for IntervalMap-0.5.3.1..
[1 of 9] Compiling Data.IntervalMap.Interval ( Data/IntervalMap/Interval.hs, dist/build/Data/IntervalMap/Interval.o )
[2 of 9] Compiling Data.IntervalMap.Generic.Interval ( Data/IntervalMap/Generic/Interval.hs, dist/build/Data/IntervalMap/Generic/Interval.o )
[3 of 9] Compiling Data.IntervalMap.Generic.Base ( Data/IntervalMap/Generic/Base.hs, dist/build/Data/IntervalMap/Generic/Base.o )

Data/IntervalMap/Generic/Base.hs:254:10: error:
    • Could not deduce (Semigroup (IntervalMap i v))
        arising from the superclasses of an instance declaration
      from the context: (Interval i k, Ord i)
        bound by the instance declaration
        at Data/IntervalMap/Generic/Base.hs:254:10-58
    • In the instance declaration for ‘Monoid (IntervalMap i v)’
    |
254 | instance (Interval i k, Ord i) => Monoid (IntervalMap i v) where
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^