diff options
Diffstat (limited to 'src/Data/Array/Nested/Internal.hs')
| -rw-r--r-- | src/Data/Array/Nested/Internal.hs | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/src/Data/Array/Nested/Internal.hs b/src/Data/Array/Nested/Internal.hs index a440ccc..fb2ba0b 100644 --- a/src/Data/Array/Nested/Internal.hs +++ b/src/Data/Array/Nested/Internal.hs @@ -961,6 +961,7 @@ mrerankP ssh sh2 f (M_Primitive sh arr) = (\a -> let M_Primitive _ r = f (M_Primitive sh1 a) in r) arr) +-- | See the caveats at @X.rerank@. mrerank :: forall sh1 sh2 sh a b. (PrimElt a, PrimElt b) => StaticShX sh -> IShX sh2 -> (Mixed sh1 a -> Mixed sh2 b) @@ -1582,6 +1583,29 @@ rrerankP sn sh2 f (Ranked arr) (\a -> let Ranked r = f (Ranked a) in r) arr) +-- | If there is a zero-sized dimension in the @n@-prefix of the shape of the +-- input array, then there is no way to deduce the full shape of the output +-- array (more precisely, the @n2@ part): that could only come from calling +-- @f@, and there are no subarrays to call @f@ on. @orthotope@ errors out in +-- this case; we choose to fill the @n2@ part of the output shape with zeros. +-- +-- For example, if: +-- +-- @ +-- arr :: Ranked 5 Int -- of shape [3, 0, 4, 2, 21] +-- f :: Ranked 2 Int -> Ranked 3 Float +-- @ +-- +-- then: +-- +-- @ +-- rrerank _ _ _ f arr :: Ranked 5 Float +-- @ +-- +-- and this result will have shape @[3, 0, 4, 0, 0, 0]@. Note that the +-- "reranked" part (the last 3 entries) are zero; we don't know if @f@ intended +-- to return an array with shape all-0 here (it probably didn't), but there is +-- no better number to put here absent a subarray of the input to pass to @f@. rrerank :: forall n1 n2 n a b. (PrimElt a, PrimElt b) => SNat n -> IShR n2 -> (Ranked n1 a -> Ranked n2 b) |