heterogeneous-product.go

/*

SeqEq is a heterogeneous product of Seq and Eq laws.
It composes two types together that "knows" how to compare sequences.
*/
type SeqEq[S, T any] struct {
  Seq[S, T]
  Eq[T]
}

// implements equality rule for sequence using Seq & Eq type classes.
func (seq SeqEq[S, T]) Equal(a, b S) bool {
  seqA := a
  seqB := b
  for !seq.Seq.IsVoid(seqA) && !seq.Seq.IsVoid(seqB) {
    headA := seq.Seq.Head(seqA)
    headB := seq.Seq.Head(seqB)
    if headA == nil || headB == nil || !seq.Eq.Equal(*headA, *headB) {
      return false
    }

    seqA = seq.Seq.Tail(seqA)
    seqB = seq.Seq.Tail(seqB)
  }

  return seq.Seq.IsVoid(seqA) && seq.Seq.IsVoid(seqB)
}