January 05, 2010 Compare in ParaSail | ||||
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From: http://parasail-programming-language.blogspot.com/2009/10/using-in-parasail-to-implement-etc.html >ParaSail skirts this issue by requiring the user to define only one operator, "=?", which returns a value from the enumeration Less, Equal, Greater, Unordered. The comparison and equality operators are defined in terms of "=?" [...] "Unordered" is used for types with only a partial ordering (or no ordering at all). "Ordered" is defined as the subtype containing only the values "Equal," "Less," and "Greater." The typical generic "Sort" operation would expect a "=?" operator whose result is guaranteed (via a postcondition) to be within the "Ordered" subtype. The "=?" operator can be used explicitly if desired, which is often convenient when searching a binary tree:< Bye, bearophile |
January 05, 2010 Re: Compare in ParaSail | ||||
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Posted in reply to bearophile | bearophile wrote:
> From:
> http://parasail-programming-language.blogspot.com/2009/10/using-in-parasail-to-implement-etc.html
>
>> ParaSail skirts this issue by requiring the user to define only one operator, "=?", which returns a value from the enumeration Less, Equal, Greater, Unordered. The comparison and equality operators are defined in terms of "=?" [...] "Unordered" is used for types with only a partial ordering (or no ordering at all). "Ordered" is defined as the subtype containing only the values "Equal," "Less," and "Greater." The typical generic "Sort" operation would expect a "=?" operator whose result is guaranteed (via a postcondition) to be within the "Ordered" subtype. The "=?" operator can be used explicitly if desired, which is often convenient when searching a binary tree:<
>
> Bye,
> bearophile
That means no static checking of ordered vs. unordered types.
Andrei
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