Re: Bignum modular types in Ada95

[kst@king.cts.com (Keith Thompson)]

If an implementation wants to provide a "bignum" type (say, a 1024-bit
or infinite-precision signed or unsigned integer type), it can do so by
taking advantage of RM95-3.5.4(26) and creating nonstandard integer types.
The implementation may place arbitrary restrictions on the operations
it supports for such types.

Here's the paragraph:

	An implementation may provide nonstandard integer types,
	descendants of root_integer that are declared outside of
	the specification of package Standard, which need not have
	all the standard characteristics of a type defined by an
	integer_type_definition. For example, a nonstandard integer
	type might have an asymmetric base range or it might not be
	allowed as an array or loop index (a very long integer). Any type
	descended from a nonstandard integer type is also nonstandard. An
	implementation may place arbitrary restrictions on the use
	of such types; it is implementation defined whether operators
	that are predefined for ``any integer type'' are defined for a
	particular nonstandard integer type. In any case, such types are
	not permitted as explicit_generic_actual_parameters for formal
	scalar types -- see 12.5.2.

As far as I know, no implementation has taken advantage of this permission.

-- 
Keith Thompson (The_Other_Keith) kst@cts.com <*>
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San Diego, California, USA
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