Pascal definition language
(After the French mathematician Blaise Pascal
(1623-1662)) A programming language designed by Niklaus Wirth
around 1970. Pascal was designed for simplicity and for teaching programming, in reaction to the complexity of ALGOL 68
. It emphasises structured programming
constructs, data structures and strong typing
. Innovations included enumeration types, subranges
, sets, variant records, and the case statement
. Pascal has been extremely influential in programming language design and has a great number of variants and descendants.
ANSI/IEEE770X3.97-1993 is very similar to ISO Pascal
but does not include conformant arrays.
ISO 7185-1983(E). Level 0 and Level 1. Changes from Jensen & Wirth's Pascal include name equivalence; names must be bound before they are used; loop index must be local to the procedure; formal procedure parameters must include their arguments; conformant array schemas.
An ALGOL-descended language designed by Niklaus Wirth on the CDC 6600 around 1967--68 as an instructional tool for elementary programming. This language, designed primarily to keep students from shooting themselves in the foot and thus extremely restrictive from a general-purpose-programming point of view, was later promoted as a general-purpose tool and, in fact, became the ancestor of a large family of languages including Modula-2 and Ada
(see also bondage-and-discipline language
). The hackish point of view on Pascal was probably best summed up by a devastating (and, in its deadpan way, screamingly funny) 1981 paper by Brian Kernighan (of K&R
fame) entitled "Why Pascal is Not My Favourite Programming Language", which was turned down by the technical journals but circulated widely via photocopies. It was eventually published in "Comparing and Assessing Programming Languages", edited by Alan Feuer and Narain Gehani (Prentice-Hall, 1984). Part of his discussion is worth repeating here, because its criticisms are still apposite to Pascal itself after ten years of improvement and could also stand as an indictment of many other bondage-and-discipline languages. At the end of a summary of the case against Pascal, Kernighan wrote:
9. There is no escape
This last point is perhaps the most important. The language is inadequate but circumscribed, because there is no way to escape its limitations. There are no casts to disable the type-checking when necessary. There is no way to replace the defective run-time environment with a sensible one, unless one controls the compiler that defines the "standard procedures". The language is closed.
People who use Pascal for serious programming fall into a fatal trap. Because the language is impotent, it must be extended. But each group extends Pascal in its own direction, to make it look like whatever language they really want. Extensions for separate compilation
, Fortran-like COMMON, string data types, internal static variables, initialisation, octal
numbers, bit operators, etc., all add to the utility of the language for one group but destroy its portability to others.
I feel that it is a mistake to use Pascal for anything much beyond its original target. In its pure form, Pascal is a toy language, suitable for teaching but not for real programming.
Pascal has since been almost entirely displaced (by C
) from the niches it had acquired in serious applications and systems programming, but retains some popularity as a hobbyist language in the MS-DOS
See also Kamin's interpreters
["The Programming Language Pascal", N. Wirth, Acta Informatica 1:35-63, 1971].
["PASCAL User Manual and Report", K. Jensen & N. Wirth, Springer 1975] made significant revisions to the language.
[BS 6192, "Specification for Computer Programming Language Pascal", British Standards Institute