Numeric.mask: def of bend-collections-laws-math@1.0.0.0
Import: import bend-collections-laws-math@1.0.0.0/spec/lib/numeric.bend as Numeric
Lines 109-117 of bend-collections-laws-math@1.0.0.0/spec/lib/numeric.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-math@1.0.0.0/spec/lib/numeric.bend&start_line=109&end_line=117

import Base

# The low k bits set, the rest clear.
def mask(+n: Nat, +k: Nat) -> Word(n):
  match n k:
    case 0n _:
      WNil{}
    case 1n+p 0n:
      WCon{False{}, mask(p, 0n)}
    case 1n+p 1n+j:
      WCon{True{}, mask(p, j)}

Uses (5):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  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