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2.1  Key Goals

Ada is a large language since it addresses many important issues relevant to
the programming of practical systems in the real world.  It is, for instance,
much larger than Pascal which, unless extended in some way, is really only
suitable for training purposes (for which it was designed) and for small 
personal programs.  Some of the key issues in Ada are

    .	Readability - it is recognized that professional programs are read
	much more often than they are written.  It is important therefore
	to avoid an over terse notation such as in APL which although allowing
	a program to be written down quickly, makes it almost impossible to be
	read except perhaps by the original author soon after it was written.

    .	Strong typing - this ensures that each object has a clearly defined 
	set of values and prevents confusion between logically distinct
	concepts.  As a consequence many errors are detected by the compiler
	which in other languages would have led to an executable but incorrect
	program.

    .	Programming in the large - mechanisms for encapsulation, separate
	compilation and library management are necessary for the writing of
	portable and maintainable programs of any size.

    .	Exception handling - it is a fact of life that programs of consequence
	are rarely correct.  It is necessary to provide a means whereby a
	program can be constructed in a layered and partitioned way so that 
	the consequences of errors in one part can be contained.

    .	Data abstraction - as mentioned earlier, extra portability and
	maintainability can be obtained if the details of the representation
	of data can be kept separate from the specifications of the logical
	operations on the data.

    .	Tasking - for many applications it is important that the program be
	conceived as a series of parallel activities rather than just a single
	sequence of actions.  Building appropriate facilties into a language
	rather than adding them via calls to an operating system gives better
	portability and reliability.

    .	Generic units - in many cases the logic of part of a program is
	independent of the types of the values being manipulated.  A mechanism
	is therefore necessary for the creation of related pieces of program
	from a single template.  This is particularly useful for the creation
	of libraries.