foldMono, ifoldMono over the outermost dimension

[kozross]

By this, I mean functions with signatures like:

foldMonoOuter :: (OuterSlice r ix e, Source r ix e, Monoid m) => (Elt r ix e -> m) -> Array r ix e -> m
ifoldMonoOuter :: (OuterSlice r ix e, Source r ix e, Monoid m) => (Int -> Elt r ix e -> m) -> Array r ix e -> m

This would be very convenient for the work I'm trying to do at the moment.

[lehins]

These functions can already be easily implemented with functions at hand. I like the idea of folding over slices, so I'll probably add a more general version in next release, plus the other ones you requested, but for now you can just use that:

ifoldMonoOuter
  :: (OuterSlice r ix e, Monoid m, Size r ix e) =>
     (Int -> Elt r ix e -> m) -> Array r ix e -> m
ifoldMonoOuter f arr = foldMono g $ range (getComp arr) 0 (headDim (size arr))
  where
    g i = f i (arr !> i)

Which seems to be doing what you want, right?

λ> a = makeArrayR U Seq (2 :. 3) (toLinearIndex (2 :. 3))
λ> ifoldMonoOuter (\i s -> [(i, s)]) a
[(0,(Array M Seq (3)
  [ 0,1,2 ])),(1,(Array M Seq (3)
  [ 3,4,5 ]))]

[kozross]

Yeah, that is definitely it.