YES

TRS:

  fst(0(),Z) -> nil()
  fst(s(),cons(Y)) -> cons(Y)
  from(X) -> cons(X)
  add(0(),X) -> X
  add(s(),Y) -> s()
  len(nil()) -> 0()
  len(cons(X)) -> s()

linear polynomial interpretations on N:

  fst_A(x1,x2) = x1 + x2 + 2
  fst#_A(x1,x2) = x1 + x2 + 2
  0_A = 1
  0#_A = 1
  nil_A = 2
  nil#_A = 2
  s_A = 1
  s#_A = 1
  cons_A(x1) = x1 + 2
  cons#_A(x1) = x1 + 2
  from_A(x1) = x1 + 3
  from#_A(x1) = x1 + 3
  add_A(x1,x2) = x1 + x2 + 1
  add#_A(x1,x2) = x1 + x2 + 1
  len_A(x1) = x1 + 1
  len#_A(x1) = x1 + 1

precedence:

  nil > fst = 0 = add > cons > s > from > len