Arith.mask_word: def of bendtorch-core@0.1.0.0
Import: import bendtorch-core@0.1.0.0/src/storage/arith.bend as Arith
Lines 358-385 of bendtorch-core@0.1.0.0/src/storage/arith.bend: https://jend.leeeet.dev/read.txt?path=bendtorch-core@0.1.0.0/src/storage/arith.bend&start_line=358&end_line=385

import Base
import bendtorch-core@0.1.0.0/src/storage/model.bend as Model

def mask_word(+m: Nat, +k: Nat, +w: Word(m), h: {Nat.is_lt(Word.to_nat(m, w), Model.capacity(k)) == True{} : Bool}) ->
  {w == Word.and(m, w, low(m, k)) : Word(m)}:
  match m:
    case 0n:
      match w:
        case WNil{}:
          {==}
    case 1n+q:
      match k:
        case 0n:
          match w:
            case WCon{+b, +t}:
              match b:
                case False{}:
                  %mask_word(q, 0n, t, lt_d1(Word.to_nat(q, t), h)) : {WCon{False{}, t} == WCon{False{}, _} : Word(1n+q)}
                  {==}
                case True{}:
                  Empty.absurd({WCon{True{}, t} == Word.and(1n+q, WCon{True{}, t}, low(1n+q, 0n)) : Word(1n+q)}, lt_zero(Nat.double(Word.to_nat(q, t)), h))
        case 1n+r:
          match w:
            case WCon{+b, +t}:
              match b:
                case False{}:
                  %mask_word(q, r, t, lt_half(False{}, Word.to_nat(q, t), r, h)) : {WCon{False{}, t} == WCon{False{}, _} : Word(1n+q)}
                  {==}
                case True{}:
                  %mask_word(q, r, t, lt_half(True{}, Word.to_nat(q, t), r, h)) : {WCon{True{}, t} == WCon{True{}, _} : Word(1n+q)}
                  {==}

Uses (15):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Empty.absurd
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.double
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.is_lt
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Word
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Word.Con
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Word.Nil
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Word.and
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Word.to_nat
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/storage/arith.bend&name=low
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/storage/arith.bend&name=lt_d1
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/storage/arith.bend&name=lt_half
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/storage/arith.bend&name=lt_zero
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/storage/model.bend&name=capacity