Generic.binpow: def of bend-collections-laws-math@1.0.0.0
Import: import bend-collections-laws-math@1.0.0.0/spec/math/generic.bend as Generic
Lines 263-271 of bend-collections-laws-math@1.0.0.0/spec/math/generic.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-math@1.0.0.0/spec/math/generic.bend&start_line=263&end_line=271

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

# right-to-left binary exponentiation: acc *= base on a 1 bit, base *= base
# while bits remain, each product rounded (k = 0 is a fixed point, so any
# fuel past k's bit length gives the same result)
def binpow(~T: Data, ~op: N.Op<T> -> T, fuel: Nat, +k: Nat, +base: T, +acc: T) -> T:
  match fuel:
    case 0n:
      acc
    case 1n+f:
      binpow(~T, ~op, f, Nat.div(k, 2n), pick(T, Nat.is_lt(1n, k), op(N.Mul{base, base}), base), pick(T, Nat.is_eq(Nat.mod(k, 2n), 1n), op(N.Mul{acc, base}), acc))

Uses (7):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.div
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.is_eq
  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=Nat.mod
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-math@1.0.0.0/spec/math/generic.bend&name=pick
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-math@1.0.0.0/src/math/num.bend&name=Op