72 Chapter 2 Evolution of the Major Programming Languages
APL was first described in the book from which it gets its name, A Programming
Language (Iverson, 1962). In the mid-1960s, the first implementation of APL
was developed at IBM.
APL has a large number of powerful operators that are specified with a
large number of symbols, which created a problem for implementors. Initially,
APL was used through IBM printing terminals. These terminals had special
print balls that provided the odd character set required by the language. One
reason APL has so many operators is that it provides a large number of unit
operations on arrays. For example, the transpose of any matrix is done with a
single operator. The large collection of operators provides very high expressiv-
ity but also makes APL programs difficult to read. Therefore, people think of
APL as a language that is best used for “throw-away” programming. Although
programs can be written quickly, they should be discarded after use because
they are difficult to maintain.
APL has been around for nearly 50 years and is still used today, although
not widely. Furthermore, it has not changed a great deal over its lifetime.2.9.2 Origins and Characteristics of SNOBOL
SNOBOL (pronounced “snowball”; Griswold et al., 1971) was designed in the
early 1960s by three people at Bell Laboratories: D. J. Farber, R. E. Griswold,
and I. P. Polonsky (Farber et al., 1964). It was designed specifically for text
processing. The heart of SNOBOL is a collection of powerful operations for
string pattern matching. One of the early applications of SNOBOL was for
writing text editors. Because the dynamic nature of SNOBOL makes it slower
than alternative languages, it is no longer used for such programs. However,
SNOBOL is still a live and supported language that is used for a variety of
text-processing tasks in several different application areas.2.10 The Beginnings of Data Abstraction: SIMULA 67
Although SIMULA 67 never achieved widespread use and had little impact on
the programmers and computing of its time, some of the constructs it intro-
duced make it historically important.2.10.1 Design Process
Two Norwegians, Kristen Nygaard and Ole-Johan Dahl, developed the lan-
guage SIMULA I between 1962 and 1964 at the Norwegian Computing Cen-
ter (NCC) in Oslo. They were primarily interested in using computers for
simulation but also worked in operations research. SIMULA I was designed
exclusively for system simulation and was first implemented in late 1964 on a
UNIVAC 1107 computer.