> To lookup a rel-value, say "printable", a client programmer would do like this, since HAL is optimized for the simple/most-used use case:

>   var url = data._links["printable"].href;

> But what happens if the server decides to throw in multiple links for the same rel-value, for instance both PDF and Word representations of the printable stuff? Well, the above code breaks since data._links["printable"] would become an array instead of a single value.

> Now a robust client has to write code like this:

>   var url = null;
>   if (data._links["printable"] IS ARRAY)
>     then lookup in that array
>   else
>     select single value.

> Unfortunately the dictionary approach encourages programmers to write the simple client code, assuming there will only be one link for each rel-value. This means encouraging programmers to write code that will break when the server decides to throw in multiple links for each rel-value.

> A robust client would always have to write code that somehow respects that it may have to traverse an array to find the link it is looking for. So why not always use an array like this:

>   _links : [
>     { rel="printable", type="pdf", href="..." },
>     { rel="printable", type="word", href="..." }
>   ];

> In that way we encourage (force) client programmers to write code that always iterates through the link array - instead of encouraging them to write brittle code that will break later on?