Differences between version 15 and predecessor to the previous major change of Pascal.
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| Newer page: | version 15 | Last edited on Wednesday, November 19, 2003 5:47:26 pm | by AristotlePagaltzis | Revert |
| Older page: | version 1 | Last edited on Wednesday, February 26, 2003 6:55:32 pm | by GlynWebster | Revert |
@@ -1,26 +1,45 @@
-A ProgrammingLanguage
by Nicolas [Wirth]
. Once very popular in schools before students started whining they wanted to learn [C].
+An ImperativeProgrammingLanguage designed
by NicolasWirth as a teaching language
. Once very popular in schools before students started whining that
they wanted to learn [C]. The ancestor of the language in [Borland]'s [Delphi] and [Kylix] [GUI] development environments, which added ObjectOrientation
.
!!! A Sample
-''(I
'm off finding one right now.
)''
+ __function__ plural (noun : __string__) : __string__;
+ { Returns the plural version of a noun. }
+ __var__
+ i : integer;
+ __begin__
+ __case__ noun[[length(noun)] __of__
+
's
': __if__ noun[[length
(noun)-1] =
'e' __then__
+ plural := noun
+ __else__
+ plural := noun + 'es';
+ 'y': __begin__
+ delete(noun, length(noun
), 1);
+ plural := noun +
'ies
';
+ __end__;
+ __else__ plural := noun + 's';
+ __end__;
+ __end__; {plural}
+
+(This is in the TurboPascal dialect of Pascal.)
!!! History
-Pascal became popular very quickly because the original compiler[3]
was designed to be very easy to [port]. It was written in Pascal and compiled to ByteCodes
, called ''P-Code''. All anyone had to do to get a Pascal compiler working on a new machine was to write a
simple P-Code VirtualMachine for it -- they could hack the compiler around to general
proper MachineCode later.
+Pascal became popular very quickly because the original compiler was designed to be very easy to [port]. It was written in Pascal and compiled to [ByteCode]s
, called ''P-Code''. All anyone had to do to get a Pascal compiler working on a new machine was to write the
simple P-Code VirtualMachine for it -- they could hack the compiler around to generate
proper MachineCode later. This meant that Pascal spread very quickly through the world's Universities. They began teaching in Pascal, because it was a very good language to demonstrate structured programming in -- a new idea and as such a hot topic at the time
.
-This meant that Pascal spread very quickly through the world's Universities. They began teaching in Pascal, because it was a very good langauge to demonstate StructuredProgramming in -- a topic that was in vogue at the time[1].
-
-and
could barely handle strings. BrianKernighan famously described Pascal's problems in [Why Pascal is Not My Favorite Programming Language |http://www.lysator.liu.se/c/bwk-on-pascal.html][2
]. These
limitations mean
that Pascal immediately
splintered into dialects as people hacked in these
missing features in incompatible ways. [C] did not have this problem, so it gradually took over from the Pascal dialects.
+Standard Pascal was a
nice language with terrible limitations: Pascal programs could not open files by name,
could barely handle strings and could only pass arrays of predetermined sizes to functions
. BrianKernighan famously described Pascal's problems in [Why Pascal is Not My Favorite Programming Language |http://www.lysator.liu.se/c/bwk-on-pascal.html]. It has to be noted that NicolasWirth had already addressed most of Pascal's problems in his follow-up language
[Modula2
] ''before'' BrianKernighan wrote this paper
. In some places BrianKernighan seems to be just complaining that Pascal is not [C]. At any rate, these
limitations meant
that Pascal splintered into dialects as people hacked in missing features in incompatible ways. [C] did not have this problem, so it gradually took over from the Pascal dialects.
!!! Implementations
-The most successful Pascal dialect has been Borland's TurboPascal. Further extended with [Modula2]-like modules and [C++]-like [OOP] it became [Delphi], which exists on
[Linux] nowadays under the name [Kylix].
+The Pascal grammer has maps very nicely to a RecursiveDescentParser struture and for this reason in it the language of choice when writing a RecursiveDescentParser by hand.
+
+
The most successful Pascal dialect has been Borland's TurboPascal. There are two OpenSource Pascal compilers for
[Linux]:
-The two OpenSorce Pascal compilers for [Linux] are:
[GNU Pascal | http://www.gnu-pascal.de/] and
[Free Pascal | http://www.freepascal.org/]. Free Pascal tend more towards TurboPascal compatability.
+*
[GNU Pascal | http://www.gnu-pascal.de/]
+*
[Free Pascal | http://www.freepascal.org/]
-----
-[1] it hasn't gone away: programmers just take it for granted that code should be structured now
.
+Free Pascal tends more towards TurboPascal compatibility
.
-[2] Take this with a little grain of salt
: Nicolas [Wirth
] had already addressed most of
Pascal's problems in his next langauge [Modula2] ''before'' BrianKernighan wrote this paper, and in some places BrianKernighan seems
to be
just complaining that Pascal is not [C]
.
+The online book
[Pascal Implementation
: A Book and Sources | http://www.cwi.nl/~steven/pascal/
] walks you through the source code to the original
Pascal compiler. It
's educational
to read
just as an extended critique of a non-trivial program
.
-[3] The online book [Pascal Implementation: A Book and Sources | http://www.cwi.nl/~steven/pascal/] walks you through the source code to this compiler. It's educational to read just as an extended critique of a non
-trivial program.
+-----
+CategoryProgrammingLanguages, CategoryImperativeProgrammingLanguages, CategoryMachineOrientedProgrammingLanguages
