Enhanced type guard syntax]

[Thomas Arts]

> perhaps this:
> 
>      f({list_of_integers,X}) ->

this is inflexible for a type checker. The tuple notation is fine, but
the verbose way of writing the atom hides the semantics.
This is very clear in:

>      f({dictionary_of_key_value_pairs,X},{key_for_dictionary,Y}) ->

How do you know that there is a relation between the key in the first atom
and the key in the second atom? They might refer to completely different
things. That is where variables come in.

/Thomas