[eeps] EEP8: parametrized types

Fred Hebert <>
Thu Dec 3 14:24:32 CET 2009


try something like "-spec size( orddict(_,_) ) -> non_neg_integer()." which
should tell it not to care about the type of the arguments.

On Thu, Dec 3, 2009 at 6:25 AM, French, Mike <
> wrote:

>
> I have a minor issue with parametrized types (R13B01).
>
> Using the example in the EEP:
>
>  -type orddict(K,V) :: [{K,V}].
>
> The question then becomes how to specify orddict:size/1 ?
> let's try:
>
>  -spec size( orddict(K,V) ) -> non_neg_integer().
>
>  Error:  type variable 'K' is only used once (is unbound)
>  Error:  type variable 'V' is only used once (is unbound)
>
> The only workaround seems to be to declare another
> unparametrized version of the same type:
>
>  -type orddict(K, V) :: [{K, V}].
>  -type orddict()     :: [tuple()].
>
> Which works, but it seems a bit excessive to require both styles of
> declaration.
>
> My suggestion would be to allow unbound type variables on the LHS of spec ?
> or perhaps demote the status from Error to Warning ?
>
> Mike
>
>
>
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