Decimal.Decimal.frac.go: def of bend-kit-bignum@0.1.0.0
Import: import bend-kit-bignum@0.1.0.0/decimal.bend as Decimal
Lines 102-130 of bend-kit-bignum@0.1.0.0/decimal.bend: https://jend.leeeet.dev/read.txt?path=bend-kit-bignum@0.1.0.0/decimal.bend&start_line=102&end_line=130

import Base
import bend-kit-bignum@0.1.0.0/bigint.bend as Big

# Each step divides d by 2 or 5 and scales n to match, so a d of D digits
# needs fewer than 4D steps; f is that bound.
def Decimal.frac.go(f: Nat, n: Big.BigInt, k: Nat, one: Bool,
  t2: Bool & Big.BigInt, t5: Bool & Big.BigInt) -> Maybe<&2, Decimal>:
  match f:
    case 0n:
      None{}
    case 1n+g:
      match one:
        case True{}:
          Some{Decimal{n, k}}
        case False{}:
          (z2, q2) = t2
          match z2:
            case True{}:
              +d = {q2 : Big.BigInt}
              Decimal.frac.go(g, Big.BigInt.mul(n, Big.BigInt.from_u32(5)),
                1n+k, Decimal.is_one(d), Decimal.divk(d, 2),
                Decimal.divk(d, 5))
            case False{}:
              (z5, q5) = t5
              match z5:
                case True{}:
                  +d = {q5 : Big.BigInt}
                  Decimal.frac.go(g, Big.BigInt.mul(n, Big.BigInt.from_u32(2)),
                    1n+k, Decimal.is_one(d), Decimal.divk(d, 2),
                    Decimal.divk(d, 5))
                case False{}:
                  None{}

Uses (11):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Pair
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Sigma
  https://jend.leeeet.dev/definition.txt?path=bend-kit-bignum@0.1.0.0/bigint.bend&name=BigInt
  https://jend.leeeet.dev/definition.txt?path=bend-kit-bignum@0.1.0.0/bigint.bend&name=BigInt.from_u32
  https://jend.leeeet.dev/definition.txt?path=bend-kit-bignum@0.1.0.0/bigint.bend&name=BigInt.mul
  https://jend.leeeet.dev/definition.txt?path=bend-kit-bignum@0.1.0.0/decimal.bend&name=Decimal
  https://jend.leeeet.dev/definition.txt?path=bend-kit-bignum@0.1.0.0/decimal.bend&name=Decimal.divk
  https://jend.leeeet.dev/definition.txt?path=bend-kit-bignum@0.1.0.0/decimal.bend&name=Decimal.is_one