why interpolation works inside ng-show and not inside ng-click

// template

      <div ng-controller="myController">
        <input type="text" ng-model="name">
        <p>{{name}}</p>
        <p>{{10+10}}</p>
        <button type="button" ng-click="{{myFunction()}}">click Me !!</button>

        <p ng-show="{{myFunction()}}">The name is {{ name | uppercase }}</p>

      </div>

// Controller

myApp.controller('myController', function ($scope) {

  $scope.name = 'Ranka';
  $scope.myFunction = function(){
    return true;
  };

});

Here it is failing in case of ng-click

angular.js:14525 Error: [$parse:syntax] Syntax Error: Token '{' invalid key at column 2 of the expression [{{myFunction()}}] starting at [{myFunction()}}].