Bigint.Mag.sub: def of bend-kit-bignum@0.1.0.0
Import: import bend-kit-bignum@0.1.0.0/bigint.bend as Bigint
Lines 90-99 of bend-kit-bignum@0.1.0.0/bigint.bend: https://jend.leeeet.dev/read.txt?path=bend-kit-bignum@0.1.0.0/bigint.bend&start_line=90&end_line=99

import Base

# a - b - w for a >= b + w. Leaves zero limbs on top: callers norm.
def Mag.sub(a: List<&2, U32>, b: List<&2, U32>, +w: U32) -> List<&2, U32>:
  match a b:
    case Con{x, xs} Con{y, ys}:
      +t = (x + 10000 - y - w : U32)
      Con{(t % 10000 : U32), Mag.sub(xs, ys, (1 - t / 10000 : U32))}
    case s Nil{}:
      Mag.dec(s, U32.is_zero(w), w)
    case Nil{} s:
      Nil{}

Uses (8):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.add
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.div
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.is_zero
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.mod
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.sub
  https://jend.leeeet.dev/definition.txt?path=bend-kit-bignum@0.1.0.0/bigint.bend&name=Mag.dec