There are few things in this business that are more fun than
designing a new computer language, and the very latest is Ada - the
Department of Defense's new supertoy. Ada, as you know, has been
designed to replace outmoded and obsolete languages such as COBOL
and FORTRAN.
The problem is that this cycle takes 20 to 30 years and
doesn't start until we're really convinced present languages are no
good. We can short-circuit this process by starting on Ada's
replacement right now. Then, by the time we decide Ada is
obsolete, its replacement will be ready.
The new generation of language designers has taken to naming
its brainchildren after real people rather than resorting to the
usual acronyms. Pascal is named after the first person to build a
calculating machine and Ada is named after the first computer
programmer. As our namesake, we chose Charles Babbage, who died in
poverty while trying to finish building the first computer. The
new language is thus named after the first systems designer to go
over budget and behind schedule.
Babbage is based on language elements that were discovered
after the design of Ada was completed. For instance, C. A. R.
Hoare, in his 1980 ACM Turing Award lecture, told of two ways of
constructing a software design: "One way is to make it so simple
that there are obviously no deficiencies and the other way is to
make it so complicated that there are no obvious deficiencies."
The designers of Babbage have chosen a third alternative - a
language that has only obvious deficiencies. Babbage programs are
so unreliable that maintenance can begin before system integration
is completed. This guarantees a steady increase in the programming
job marketplace.
Like Pascal, Ada uses "strong typing" to avoid errors caused
by mixing data types. The designers of Babbage advocate "good
typing" to avoid errors caused by misspelling the words in your
program. Later versions of Babbage will also allow "touch typing,"
which will fill a long-felt need.
A hotly contested issue among language designers is the method
for passing parameters to subfunctions. Some advocate "call by
name," others prefer "call by value." Babbage uses a new method -
"call by telephone." This is especially effective for
long-distance parameter passing.
Ada stresses the concept of software portability. Babbage
encourages hardware portability. After all, what good is a
computer if you can't take it with you?
It's a good sign if your language is sponsored by the
government. COBOL had government backing, and Ada is being funded
by the Department of Defense. After much negotiation, the
Department of Sanitation has agreed to sponsor Babbage.
No subsets of Ada are allowed. Babbage is just the opposite.
None of Babbage is defined except its extensibility - each user
must define his own version. To end the debate of large languages
versus small, Babbage allows each user to make the language any
size he wants. Babbage is the ideal language for the "me"
generation. The examples that follow will give you some idea of
what Babbage looks like.
Structured languages banned GOTOs and multiway conditional
branches by replacing them with the simpler IF-THEN-ELSE structure.
Babbage has a number of new conditional statements that act like
termites in the structure of your program:
WHAT IF: Used in simulation languages. Branches before
evaluating test conditions.
OR ELSE: Conditional threat, as in: "Add these two numbers OR
ELSE!"
WHY NOT?: Executes the code that follows in a devil-may-care
fashion.
WHO ELSE?: Used for polling during I/O operations.
ELSEWHERE: This is where your program really is when you
think it's here.
GOING GOING GONE: For writing unstructured programs. Takes
a random branch to another part of your program. Does the
work of 10 GOTOs.
For years, programming languages have used "FOR," "DO UNTIL," "DO
WHILE," etc. to mean "LOOP." Continuing with this trend, Babbage
offers the following loop statements:
DON'T DO WHILE NOT: This loop is not executed if the test
condition is not false (or if it's Friday afternoon).
DIDN'T DO: The loop executes once and hides all traces.
CAN'T DO: The loop is pooped.
WON'T DO: The CPU halts because it doesn't like the code
inside the loop. Execution can be resumed by typing "May I"
at the console.
MIGHT DO: Depends on how the CPU is feeling. Executed if the
CPU is "up," not executed if the CPU is "down" or if its
feelings have been hurt.
DO UNTO OTHERS: Used to write the main loop for timesharing
systems so that they will antagonize the users in a uniform
manner.
DO-WAH: Used to write timing loops for computer-generated
music (Rag Timing).
Every self-respecting language has a case statement to implement
multiway branching. ALGOL offers an indexed case statement and
Pascal has a labeled case statement. Not much of a choice.
Babbage offers a variety of interesting case statements:
The JUST-IN-CASE Statement: For handling afterthoughts and
fudge factors. Allows you to multiply by zero to correct for
accidentally dividing by zero.
The BRIEF CASE Statement: To encourage portable software.
The OPEN-AND-SHUT CASE Statement: No proof of correctness is
necessary with this one.
The IN-ANY-CASE Statement: This one always works.
The HOPELESS CASE Statement: This one never works.
The BASKET CASE Statement: A really hopeless case.
The Babbage Language Design Group is continuously evaluating new
features that will keep its users from reaching any level of
effectiveness. For instance, Babbage's designers are now
considering the ALMOST EQUALS sign, used for comparing two
floating-point numbers. This new feature "takes the worry out of
being close."
No language, no matter how bad, can stand on its own. We need
a really state-of-the-art operating system to support Babbage.
After trying several commercial systems, we decided to write a
"virtual" operating system. Everybody has a virtual memory
operating system so we decided to try something a little different.
Our new operating system is called the Virtual Time Operating
System (VTOS). While virtual memory systems make the computer's
memory the virtual resource, VTOS does the same thing with CPU
processing time.
The result is that the computer can run an unlimited number of
jobs at the same time. Like the virtual memory system, which
actually keeps part of memory on disk, VTOS has to play tricks to
achieve its goals. Although all of your jobs seem to be running
right now, some of them are actually running next week.
As you can see, Babbage is still in its infancy. The Babbage
Language Design Group is seeking suggestions for this powerful new
language and as the sole member of this group (all applications for
membership will be accepted), I call on the computing community for
help in making this dream a reality.