PermuteBuildProof.source_index: def of bendtorch-core@0.1.0.0
Import: import bendtorch-core@0.1.0.0/src/tensor/permute_build_proof.bend as PermuteBuildProof
Lines 156-168 of bendtorch-core@0.1.0.0/src/tensor/permute_build_proof.bend: https://jend.leeeet.dev/read.txt?path=bendtorch-core@0.1.0.0/src/tensor/permute_build_proof.bend&start_line=156&end_line=168

import Base
import bendtorch-core@0.1.0.0/src/shape/core.bend as Shape
import bendtorch-core@0.1.0.0/src/tensor/axis_spec.bend as Axis
import bendtorch-core@0.1.0.0/src/tensor/layout.bend as Layout
import bendtorch-core@0.1.0.0/src/tensor/observation.bend as Values
import bendtorch-core@0.1.0.0/src/tensor/permute_build.bend as Build

# The build's index map is `permute_source_index`.
def source_index(+input: Shape.Shape, +axes: List<&2, U32>, +index: Nat) ->
  {Build.source(Build.recipe(Build.Request{input, axes}), index) == Values.permute_source_index(input, axes, index) : Nat}:
  +dims = Shape.dimensions(input)
  +out = Shape.naturals(Axis.order(U32, dims, Shape.naturals(axes)))
  +x = U32.to_nat(U32.from_nat(index))
  +picks = Build.picks(Shape.rank_dimensions(dims), Shape.naturals(axes), out, 0n)
  Equal.sym(Nat, Values.permute_source_index(input, axes, index), Build.found(picks, Build.strides(Shape.naturals(dims)), index),
    %Equal.sym(Maybe<&2, List<&2, U32>>, Axis.scatter(U32, Shape.rank_dimensions(dims), Shape.naturals(axes), Shape.words(Shape.digits(out, x)), 0n),
      coordinates_of(picks, x), scatter_digits(Shape.rank_dimensions(dims), Shape.naturals(axes), out, x, 0n)) :
      {U32.to_nat(Maybe.default(&2, U32, Layout.reference_source_coordinates(dims, _), 0)) ==
        Build.found(picks, Build.strides(Shape.naturals(dims)), index) : Nat}
    found_coordinates(dims, picks, index))

Uses (27):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Equal.sym
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe.default
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.from_nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.to_nat
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/shape/core.bend&name=Shape
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/shape/core.bend&name=digits
  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=naturals
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/shape/core.bend&name=rank_dimensions
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/shape/core.bend&name=words
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/axis_spec.bend&name=order
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/axis_spec.bend&name=scatter
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/layout.bend&name=reference_source_coordinates
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/observation.bend&name=permute_source_index
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/permute_build.bend&name=Request
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/permute_build.bend&name=found
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/permute_build.bend&name=picks
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/permute_build.bend&name=recipe
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/permute_build.bend&name=source
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/permute_build.bend&name=strides
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/permute_build_proof.bend&name=coordinates_of
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/permute_build_proof.bend&name=found_coordinates
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/tensor/permute_build_proof.bend&name=scatter_digits