/*

  Strip a set of characters from a string Picat.

  From Rosetta code:
  http://rosettacode.org/wiki/Strip_a_set_of_characters_from_a_string
  """
  The task is to create a function that strips a set of characters 
  from a string. The function should take two arguments: the first argument 
  being a string to stripped and the second, a string containing the set 
  of characters to be stripped. The returned string should contain the 
  first string, stripped of any characters in the second argument:

     print stripchars("She was a soul stripper. She took my heart!","aei")
     Sh ws  soul strppr. Sh took my hrt!
  """


  Model created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/

main => go.

go => 
   S = "She was a soul stripper. She took my heart!",
   println(stripchars(S, "aei")),
   stripchars2(S, "aei",S2),
   println(S2),
   nl.

% List comprehension
stripchars(String, Chars) = [C : C in String, not(membchk(C,Chars))].

% Recursion
stripchars2(String,Chars, Res) =>
 stripchars2(String, Chars, [], Res).

stripchars2([], _Chars, Res, Res).
stripchars2([H|T], Chars, Res1, Res) :-
  membchk(H,Chars),
  stripchars2(T, Chars, Res1, Res).
stripchars2([H|T], Chars, Res1, [H|Res]) :-
  stripchars2(T, Chars, Res1, Res).