%!PS

% begin included library code
% see https://codeberg.org/Firedrake/postscript-libraries/
/dget {
    3 1 roll
    2 copy
    known {
        get exch pop
    } {
        pop pop
    } ifelse
} bind def

/filter { % array proc(bool) -> array
    1 dict begin
    /p exch def
    [ exch
      {
          dup p not
          {
              pop
          } if
      } forall
    ]
    end
} bind def

/keys { % dict -> array of dict keys
    [ exch
      {
          pop
      } forall
    ]
} bind def

/test.end {
    ( ) print
    test.count 0 gt {
        (Passed ) print
        test.pass (...) cvs print
        (/) print
        test.count (...) cvs print
        ( \() print
        test.pass 100 mul test.count idiv (...) cvs print
        (%\)) print
        (\r\n) print
    } if
} bind def

/test.start {
    print (:) print
    /test.pass 0 def
    /test.count 0 def
} bind def

/test {
    /test.count test.count 1 add def
    {
        /test.pass test.pass 1 add def
    } {
        ( ) print
        test.count (....) cvs print
        (-fail) print
    } ifelse
} bind def


% end included library code

/countcommon {
    0 dict begin
    /bc 0 dict def
    {
        /w exch def
        bc w bc w 0 dget 1 add put
    } forall
    /ac 0 dict def
    {
        /w exch def
        ac w ac w 0 dget 1 add put
    } forall
    ac keys {
        /k exch def
        ac k get 1 eq
        bc k 0 dget 1 eq
        and
    } filter length
    end
} bind def

(countcommon) test.start
[(Perl) (is) (my) (friend)] [(Perl) (and) (Raku) (are) (friend)] countcommon 2 eq test
[(Perl) (and) (Python) (are) (very) (similar)] [(Python) (is) (top) (in) (guest) (languages)] countcommon 1 eq test
[(Perl) (is) (imperative) (Lisp) (is) (functional)] [(Crystal) (is) (similar) (to) (Ruby)] countcommon 0 eq test
test.end