def reference

bendtorch-core@0.1.0.0 · src/tensor/permute_build_proof.bend:176

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/permutation_mapping.bend as Mapping

176# The mapping a permute's plan gives an output index names the input index
177# `permute_source` names, and it lies inside the input.
178def reference(+input: Shape.Shape, +axes: List<&2, U32>, +plan: Layout.Plan<input, axes>, +index: U32,
179  +mapping: Layout.Mapping<input, axes, plan, index>) ->
180  {Some{Layout.source_index(input, axes, plan, index, mapping)} == Values.permute_source(input, axes, index) : Maybe<&2, U32>}:
181  Equal.trans(Maybe<&2, U32>, Some{Layout.source_index(input, axes, plan, index, mapping)}, Layout.reference_source(input, axes, plan, index),
182    Values.permute_source(input, axes, index),
183    Mapping.mapping_reference(input, axes, plan, index, mapping),
184    Equal.cong(List<&2, U32>, Maybe<&2, U32>,
185      dimensions => Layout.reference_source_coordinates(Shape.dimensions(input),
186        Axis.scatter(U32, Shape.rank_dimensions(Shape.dimensions(input)), Shape.naturals(axes),
187          Shape.words(Shape.digits(Shape.naturals(dimensions), U32.to_nat(index))), 0n)),
188      Shape.dimensions(Layout.output(input, axes, plan)), Axis.order(U32, Shape.dimensions(input), Shape.naturals(axes)),
189      Mapping.permutation_dimensions_order(input, axes, plan)))