Signed.narrow: def of bendtorch-core@0.1.0.0
Import: import bendtorch-core@0.1.0.0/src/tensor/signed.bend as Signed
Lines 346-357 of bendtorch-core@0.1.0.0/src/tensor/signed.bend: https://jend.leeeet.dev/read.txt?path=bendtorch-core@0.1.0.0/src/tensor/signed.bend&start_line=346&end_line=357

import Base
import bendtorch-core@0.1.0.0/src/shape/core.bend as Shape
import bendtorch-core@0.1.0.0/src/tensor/core.bend as Core
import bendtorch-core@0.1.0.0/src/tensor/slice.bend as Slice

# PyTorch's input.narrow(dim, start, length) at a signed axis with a signed
# start. PyTorch takes a start in -extent..extent: Last{k} with k below the
# extent is extent - 1 - k, and one before -extent is OutOfRange. A First
# start past the extent is refused by the unsigned narrow, which checks
# start + length against the extent, with the same code. A length is a
# U32, so PyTorch's negative lengths cannot be written.
def narrow(input: Core.Dynamic, dim: Position, +start: Position, +length: U32) ->
  Core.Dynamic & Result<&2, &1, Slice.Error, Core.Dynamic>:
  Core.Packed{+shape, tensor} = input
  +axis = wrap(Shape.rank(shape), dim)
  +n = extent(Shape.dimensions(shape), axis)
  narrow_started(shape, tensor, axis, wrap(n, start), length, before(n, start))

Uses (12):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Pair
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Result
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/shape/core.bend&name=dimensions
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/shape/core.bend&name=rank
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/core.bend&name=Dynamic
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/signed.bend&name=Position
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/signed.bend&name=before
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/signed.bend&name=extent
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/signed.bend&name=narrow_started
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/signed.bend&name=wrap
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/slice.bend&name=Error