Nested array represented as a flat array of elements, and a segment descriptor that describes how the elements are partitioned into the sub-arrays. Using this representation for multidimentional arrays is significantly more efficient than using a boxed array of arrays, as there is no need to allocate the sub-arrays individually in the heap.

With a nested type like: Array N (Array N (Array U Int)), the concrete representation consists of five flat unboxed vectors: two for each of the segment descriptors associated with each level of nesting, and one unboxed vector to hold all the integer elements.

UNSAFE: Indexing into raw material arrays is not bounds checked. You may want to wrap this with a Checked layout as well.

O(size src) Convert some lists to a nested array.

O(size src) Convert a triply nested list to a triply nested array.

Apply a function to all the elements of a doubly nested array, preserving the nesting structure.

O(1). Produce a nested array by taking slices from some array of elements.

This is a constant time operation, as the representation for nested vectors just wraps the starts, lengths and elements vectors.

Segmented concatenation. Concatenate triply nested vector, producing a doubly nested vector.

• Unlike the plain concat function, this operation is performed entirely on the segment descriptors of the nested arrays, and does not require the inner array elements to be copied.

> import Data.Repa.Nice
> nice $ concats $ fromListss U [["red", "green", "blue"], ["grey", "white"], [], ["black"]]
["red","green","blue","grey","white","black"]

O(len src). Given predicates which detect the start and end of a segment, split an vector into the indicated segments.

O(len src). Given a terminating value, split an vector into segments.

The result segments do not include the terminator.

> import Data.Repa.Nice
> nice $ segmentOn (== ' ') (fromList U "fresh   fried fish  ") 
["fresh "," "," ","fried ","fish "," "]

O(len src). Like segment, but cut the source array twice.

O(len src). Given field and row terminating values, split an array into rows and fields.

For each segment of a nested array, trim elements off the start and end of the segment that match the given predicate.

For each segment of a nested array, trim elements off the end of the segment that match the given predicate.

For each segment of a nested array, trim elements off the start of the segment that match the given predicate.

Ragged transpose of a triply nested array.

• This operation is performed entirely on the segment descriptors of the nested arrays, and does not require the inner array elements to be copied.