That's a bit convoluted.
CAVEAT: This is very, very hacky and just absolutely exactly what you're NOT supposed to do in angular, but I guess you know that and the library is making your life hard...
First, unlike onclick, an href won't interpret a string as javascript. Instead, you'd have to use
<a href="javascript:someFunction()"></a>
But this alone won't make it work, because someFunction() is not a method on the document, but on the controller, so we need to get the controller first:
<a href="javascript:angular.element(
document.getElementById('myController')).scope().someFunction();"></a>
Where myController refers to the DOM element that is decorated with ng-controller, e.g.
<div data-ng-controller="SomeController" id="myController"> ... </div>
If someFunction modifies the state of the view, you'll also need to use $scope.apply, i.e.
<a href="javascript:angular.element(document.getElementById('myController')).
scope().$apply(someFunction)"></a>
Note that you don't need the {{ }} syntax, because you're calling javascript directly, you're not asking angular to modify your markup.