Generic.fact_go: def of bend-collections-laws-math@1.0.0.0
Import: import bend-collections-laws-math@1.0.0.0/src/math/generic.bend as Generic
Lines 444-454 of bend-collections-laws-math@1.0.0.0/src/math/generic.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-math@1.0.0.0/src/math/generic.bend&start_line=444&end_line=454

import Base
import bend-collections-laws-math@1.0.0.0/src/math/num.bend as N

# 2 * 3 * ... * n: i runs up to n, stopping at the first overflow
def fact_go(~T: Data, ~op: N.Op<T> -> T, ~test: N.Test<T> -> Bool, fuel: Nat, +i: T, +n: T, st: T & Bool, more: Bool) -> Maybe<&2, T>:
  match fuel st more:
    case 0n _ _:
      None{}
    case 1n+f Tuple{a, False{}} _:
      None{}
    case 1n+f Tuple{+a, True{}} False{}:
      Some{a}
    case 1n+f Tuple{+a, True{}} True{}:
      fact_go(~T, ~op, ~test, f, inc(~T, ~op, i), n, mul_by(~T, ~op, ~test, inc(~T, ~op, i), (a, True{})), test(N.Lt{inc(~T, ~op, i), n}))

Uses (9):
  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-collections-laws-math@1.0.0.0/src/math/generic.bend&name=inc
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-math@1.0.0.0/src/math/generic.bend&name=mul_by
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-math@1.0.0.0/src/math/num.bend&name=Op
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-math@1.0.0.0/src/math/num.bend&name=Test