Python Constraints in a loop

Question

I am working with the python-constraint library and a logical error has risen.

It seems to me that a similar question has been asked here but I don't understand how to apply it in my case

First I call this code

my_function(List):
  from constraint import Problem , AllDifferentConstraint
  problem = Problem()
  people = ["bob", "tom"]
  times = ["2:00", "3:00"]

  t_vars = list(map(lambda x: "t_"+x, people))
  problem.addVariables(t_vars, times)

  problem.addConstraint(AllDifferentConstraint(), t_vars)

  for person in List:
      problem.addConstraint (
          (lambda x:  
              (x == person[1])
          ),
          ["t_"+person[0]]
      )

  return problem.getSolutions()

Then I call with

my_function([["bob", "2:00"], ["tom", "3:00"]])

and it returns an empty []. Why?

However, if I enter

my_function([["bob", "2:00"]])

it returns what I want, which is [{'t_bob': '2:00', 't_tom': '3:00'}]

Answer 1

Following the guidelines from another post's answer, I came up with this solution and it works:

def generate_constrained_func(val_in_dict):
    def constraint_func(x):
        return (x == val_in_dict)
    return constraint_func

for person in List:
    if(person):
        problem.addConstraint(generate_constrained_func(person[1]), (["t_"+person[0]]))