semigroup-fold.go

type Foldable[T any] interface {
  Fold(T, []T) T
}

type Semigroup[T any] interface {
  Combine(T, T) T
}

type Folder[T any] struct{ Semigroup[T] }

func (f Folder[T]) Fold(a T, seq []T) (x T) {
  x = a
  for _, y := range seq {
    x = f.Semigroup.Combine(x, y)
  }
  return
}