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Elliotte Rusty Harold wrote: > At 12:52 PM -0700 5/7/02, Jonathan Robie wrote: > >Without the cast, max() would sort according to the string value, > >not the decimal value. > > I would propose more simply that max() and similar functions always > treat their arguments as numbers. I personally have never heard of a > max() function that operates on strings anyway. It does in Haskell: Prelude> max 1 2 2 Prelude> max "abc" "def" "def" Prelude> :type max max :: Ord a => a -> a -> a In C++, 'max' works on any type 'T' for which bool T::operator<(const T&) or bool ::operator<(const T&,const T&) is defined (which includes strings). That said, I strongly agree that for XQuery it makes more sense to have type-specific functions. Like you said: > In brief, I suggest if you > pass something to a function that expects a number, it's converted to > a number. If you pass something to a function that expects a date, > it's converted to a date. No muss, no fuss. IMO, that is an eminently more sensible approach for XQuery. With class-based polymorphism a la Haskell, a polymorphic 'max' makes sense. With ad-hoc overloading a la C++, it's still workable. But XQuery has a dynamic type system at its base with an optional static type system added on, much like Common Lisp. In languages like that, overloaded functions are _very_ tricky to specify well, tedious to implement, and unpredictable in use. It's workable if the type hierarchy is well thought-out, like the Lisp numeric tower is. Looking at the mixed bag of XSD primitive types, I have serious doubts. --Joe English jenglish@f...
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