PROOF.F_len: def of bend-osdev-bytes@0.1.1.0
Import: import bend-osdev-bytes@0.1.1.0/PROOF.bend as PROOF
Lines 310-313 of bend-osdev-bytes@0.1.1.0/PROOF.bend: https://jend.leeeet.dev/read.txt?path=bend-osdev-bytes@0.1.1.0/PROOF.bend&start_line=310&end_line=313

import Base
import bend-osdev-bytes@0.1.1.0/bytes.bend as B
import bend-osdev-u32@0.1.0.0/LAWS.bend as UL

def F_len(+ws: List<&2, B.OctByte>) -> {List.length(&2, B.OctByte, ws) == B.w8s.len.fast(ws) : Nat}:
  Equal.sym(Nat, B.w8s.len.fast(ws), List.length(&2, B.OctByte, ws),
    Equal.trans(Nat, B.w8s.len.go(ws, 0n), Nat.add(List.length(&2, B.OctByte, ws), 0n), List.length(&2, B.OctByte, ws),
      g_len(ws, 0n), UL.nat_add_zero(List.length(&2, B.OctByte, ws))))

Uses (11):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Equal.sym
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Equal.trans
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List.length
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.add
  https://jend.leeeet.dev/definition.txt?path=bend-osdev-bytes@0.1.1.0/PROOF.bend&name=g_len
  https://jend.leeeet.dev/definition.txt?path=bend-osdev-bytes@0.1.1.0/bytes.bend&name=OctByte
  https://jend.leeeet.dev/definition.txt?path=bend-osdev-bytes@0.1.1.0/bytes.bend&name=w8s.len.fast
  https://jend.leeeet.dev/definition.txt?path=bend-osdev-bytes@0.1.1.0/bytes.bend&name=w8s.len.go
  https://jend.leeeet.dev/definition.txt?path=bend-osdev-u32@0.1.0.0/LAWS.bend&name=nat_add_zero