Omissions from Ada
Here are the notable omissions from the subset:
- Only a subset of the attributes are supported:
- 'First, 'Last, and 'Length
on array objects (not on types and subtypes).
- 'Min and 'Max.
- 'Pos and 'Val.
- 'Tag.
- 'Range on array objects (not subtypes), but only as the right
operand of the membership (
in
) operator.
- 'Access, 'Unchecked_Access, and
'Unrestricted_Access (a GNAT extension).
- 'Address.
- The names in
Characters.Latin_1
are not available and
concatenation is not implemented. Thus, escape characters in strings are
not currently available.
- The component-by-component array operations (and, or,
xor, not, and relational and equality tests) are not implemented.
- There are no record or array aggregates.
- Dispatching subprogram calls are not implemented.
- The overloading algorithm is much more limited (i.e., less selective)
than that of real Ada. It makes only limited use of the context in which a subexpression
appears to resolve its meaning, and it is much looser in its rules for allowing
type matches. As a result, some function calls will be ambiguous, and the user
will be asked to choose the proper resolution.
- The new operator is not implemented.
- Entry calls are not implemented.
- Aside from printing, arithmetic operations on the native VAX floating-point
formats are not supported.