[m-dev.] switching on constant functions

[Julien Fischer]

On Mon, 22 Dec 2008, Julien Fischer wrote:

>
> On Mon, 22 Dec 2008, Ian MacLarty wrote:
>
>> Hi,
>> 
>> I'd like to be able to switch on the values of constant functions.
>> For example suppose I have the functions:
>> 
>>    :- func a = (string::(out(bound("a")))).
>>    :- func b = (string::(out(bound("b")))).
>> 
>> then I'd like to be able to write a switch like:
>> 
>>    % X has inst bound("a" ; "b") before the switch.
>>    (
>>        X = a,
>>        ...
>>    ;
>>        X = b,
>>        ...
>>    )
>> 
>> Would there be any objections to extending the language to handle this?
>> If not what would be the best way to implement it?  I was thinking of
>> replacing constant functions, whose output is an inst with a single
>> value, by that value before or in the switch detection pass.
>
> What if the type involved is abstract and imported from another module?

Obviously the second follows from the first there ;-)

Julien.
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