List.head_cons_sym: law of bend-mathlib@0.8.1.0
Import: import bend-mathlib@0.8.1.0/list.bend as List
Lines 2869-2875 of bend-mathlib@0.8.1.0/list.bend: https://jend.leeeet.dev/read.txt?path=bend-mathlib@0.8.1.0/list.bend&start_line=2869&end_line=2875

import Base

# The head of a cons is its first element, reversed to rewrite toward the simple side.
law head_cons_sym:
  for -a: Quant
  for -A: Kind(a)
  for -x: A
  for -xs: List<a, A>
  {Some{x} == List.head(a, A, x <> xs) : Maybe<a, A>}

Uses (5):
  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=List.head
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe
  https://jend.leeeet.dev/definition.txt?path=bend-mathlib@0.8.1.0/list.bend&name=head_cons