[mercury-users] abstract types.

[Peter Schachte]

> How should I implement an abstract form of lr1item? I'd like the interface
> to be the same:
> 	:- type lr1item.	% abstract
> or
> 	:- type lr1item == int.
> 
> along with:
> 	:- func lr1item(prodNum, dot, symbol).
> 	:- mode (lr1item(in, in, in) = out) is det.
> 	:- mode (lr1item(out, out, out) = in) is det.
> 
> Or should I just make another type "encoded_lr1item" and use explicit
> conversions?

I'd hope the simple bidirectional function version would work, so I'd
suggest giving that a bash, and use explicity pack/unpack operations
as a last resort.

I'd be interested to hear how it goes.

-- 
Peter Schachte                     I love deadlines. I like the whooshing
mailto:schachte at cs.mu.OZ.AU        sound they make as they fly by.
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PGP: finger schachte at 128.250.37.3  
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