TensorVjpLAWS.first_of: def of bendtorch-core@0.1.0.0
Import: import bendtorch-core@0.1.0.0/src/autograd/tensor_vjp_LAWS.bend as TensorVjpLAWS
Lines 77-90 of bendtorch-core@0.1.0.0/src/autograd/tensor_vjp_LAWS.bend: https://jend.leeeet.dev/read.txt?path=bendtorch-core@0.1.0.0/src/autograd/tensor_vjp_LAWS.bend&start_line=77&end_line=90

import Base
import bendtorch-core@0.1.0.0/src/autograd/tensor_backward.bend as Backward

# The two contributions of a VJP, when it sends exactly two.
def first_of(pass: Backward.Pass) -> Maybe<&1, Backward.Contribution>:
  Backward.Pass{saved, g, contributions} = pass
  match contributions:
    case Fail{error}:
      None{}
    case Done{Nil{}}:
      None{}
    case Done{Con{first, Nil{}}}:
      None{}
    case Done{Con{first, Con{second, Nil{}}}}:
      Some{first}
    case Done{Con{first, Con{second, Con{other, rest}}}}:
      None{}

Uses (5):
  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=Result
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/autograd/tensor_backward.bend&name=Contribution
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/autograd/tensor_backward.bend&name=Pass