List.head_cons: law of bend-mathlib@0.8.1.0
Import: import bend-mathlib@0.8.1.0/list.bend as List
Lines 1636-1642 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=1636&end_line=1642

import Base

# The head of a cons is its first element.
law head_cons:
  for -a: Quant
  for -A: Kind(a)
  for -x: A
  for -xs: List<a, A>
  {List.head(a, A, x <> xs) == Some{x} : Maybe<a, A>}

Uses (3):
  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