def FSum.fold

bend-collections-laws-crypto@1.0.0.0 · spec/math/generic.bend:256

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

256# ((0 + x0) + x1) + ..., every addition rounded
257def FSum.fold(~T: Data, ~op: N.Op<T> -> T, ~test: N.Test<T> -> Bool, xs: List<&2, T>) -> Type:
258  {G.sum(~T, ~op, ~test, xs) == Done{fold_add(~T, ~op, xs, op(N.ZeroOp{}))} : Result<&2, &2, N.NumError, T>}