def BigInt.modpow

bend-kit-bignum@0.1.0.0 · bigint.bend:452

import Base

452# b^e mod |m| in [0, |m|). None for m = 0 or e < 0.
453def BigInt.modpow(b: BigInt, e: BigInt, m: BigInt) -> Maybe<&2, BigInt>:
454  match b e m:
455    case BigInt{sb, x} BigInt{se, y} BigInt{sm, Nil{}}:
456      None{}
457    case BigInt{sb, x} BigInt{se, y} BigInt{sm, z}:
458      BigInt.modpow.go(se, sb, x, y, z)