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Beau­tiful Racket / racket school 2019

Day 3

Mission

Imple­ment these language features:

  1. printed anony­mous func­tions carry correct source loca­tion (you need to run this in a saved source file to see the line and column numbers)

    Hint: See syntax/loc

    test.rkt
    var obj = {
        'dbl' : function(x) { x + x; }
    };
    obj.dbl; // #<procedure:...test.rkt:3:12>
    var obj = {
    'dbl' : func­tion(x) { x + x; }
};
obj.dbl; // #<proce­dure:...test.rkt:3:12>
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  2. return state­ment inside func­tions

    Hint: Adapt the example in para­me­ters.

    var eq = function (x, y) {
      if ( x == y ) {
         return "yes";
      } else {
         return "no";
      }
    };

    eq(4, 4); // "yes"
    eq(4, 2); // "no"
    var eq = func­tion (x, y) {
  if ( x == y ) {
     return "yes";
  } else {
     return "no";
  }
};

eq(4, 4); // "yes"
eq(4, 2); // "no"
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Optional

  1. Make a scriptish indenter for DrRacket.

  2. Make a scriptish syntax colorer for DrRacket.

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